What Constitutes "Cross Country"
John Stephens
What legally constitutes a cross-country flight?
A local flight is pretty clearly defined as one that remains within 25 miles
of the originating airport. This definition is used in several FARs to set
limits on recreational pilots, night commercial flights with passengers if the
PIC is not IFR rated, etc. For the Private ticket, X-country flights must
include a landing at an airport at least 50 miles away. For the IFR ticket,
at least 50 hours of solo X-country time must have been logged, etc.
I can't find a clear, unqualified definition of X-country -- one that applies
to logging time as X-country time after the Private or Instrument ratings have
been obtained. Is there one? Is it 25 miles, or 50 miles? Do you have to
actually LAND at a second airport (more than 25/50 miles away), or does a
missed approach (in IFR conditions) count?
Examples:
1. VFR/IFR flight to an airport 35 miles away, touch-and-go, return to home
base. Is this time loggable as X-country?
2. IFR flight to an airport 65 miles away, instrument approach, missed
approach, return to home base. Is this time loggable as X-country?
3. Is any missed approach countable for a X-country? How far into the
approach do you have to get? Past FAF? To MDA? To DH/MAP?
If anybody knows the answers to these, I would appreciate it hearing from you.
Thanks in advance.
Lonnie C. Martin
>
>What legally constitutes a cross-country flight?
>
>PIC is not IFR rated, etc. For the Private ticket, X-country flights must
>include a landing at an airport at least 50 miles away. For the IFR ticket,
>at least 50 hours of solo X-country time must have been logged, etc.
It is _MORE THAN_ 50 nm, not "at least" 50 nm.
As for the rest of the question, a landing not at the airport of origin
makes the flight cross-country. The instructor I train with now argues that
"cross-country" time should not include time spent in multiple approaches,
or other practice that significantly extends the ATE. This seems
reasonable, but I have not seen any clear reference in the FAR or AIM.
Landing, as I understand, means that a tire squeaks; T&G counts; low or
missed approach does not count.
Lonnie
--
Lonnie C. Martin lon...@hydrogen.cchem.berkeley.edu
Geoff Peck
(John Stephens) asks about cross-country flight requirements:
> I can't find a clear, unqualified definition of X-country -- one that
> applies to logging time as X-country time after the Private or Instrument
> ratings have been obtained. Is there one? Is it 25 miles, or 50 miles?
> Do you have to actually LAND at a second airport (more than 25/50 miles
> away), or does a missed approach (in IFR conditions) count?
Well, it depends on why you wish to count something as cross-country.
If you wish to use the time to satisfy requirements for a higher rating,
then you must satisy the specific requirements outlined in the FARs for
that particular rating. To wit:
For the instrument rating, FAR 61.65(e)(1):
A total of 125 hours of pilot flight time, of which 50 hours are as
pilot in command in cross-country flight in a powered aircraft with
other than a student pilot certificate. Each cross-country flight
must have a landing at a point more than 50 nautical miles from the
original departure point.
This says that you must ***land*** at a point more than 50nm from the
original departure point. You may count the entire flight as cross
country, regardless of how circuitous a routing or how long the flight
takes, as long as it can be regarded as a single flight. (I.e., if you
flew from A 25nm to B, stayed overnight, and then flew from B 26nm to C,
and A->C is 51nm, you could not log that as cross-country for these
purposes because A->B and B->C are different flights.)
You cannot count student cross-country time towards the 50 hours of
cross-country for the instrument rating, but you can count instrument
training flights, provided that a ***landing*** is made at least 50nm from
the point of origin.
For the commercial certificate, FAR 61.129(b)(3)(ii):
50 hours of cross-country flights, each flight with a landing at a
point more than 50 nautical miles from the original departure point.
One flight must have landings at a minimum of three points, one of
which is at least 150 nautical miles from the original departure
point if the flight is conducted in Hawaii, or at least 250 nautical
miles from the original departure point if it is conducted
elsewhere.
This is very similar to the instrument rating requirements.
For the ATP, things get a bit fuzzier. FAR 61.xxx(b)(2):
(2) At least 1,500 hours of flight time as a pilot, including at
least --
(i) 500 hours of cross-country flight time; [...]
What counts as cross-country flight time is left to the discretion of the
FAA inspector who evaluates a candidate's preparation before authorizing
the candidate to take the ATP written exam. The guidelines which the FAA
publishes on this subject change from time to time. At this point, most
inspectors will question the use of a 4-hour 51nm instrument training
flight as a cross-country flight for the ATP -- the flight must appear to
have been "reasonable". At one point, the FAA allowed any flight
in which at least two navaids were used, regardless of landing locations,
to count as cross-country towards the ATP.
Bottom line: when you get this far, you should have more than enough
"real" cross-country experience. Go out and fly across the U.S. a few
times if you're in doubt. (When I went through this interview a while ago,
the FAA inspector was thumbing through the logs, and asked about an
instrument training flight which was logged as cross-country. When he
grumbled that that kind of flight shouldn't really be logged as 100%
cross-country, I suggested that I'd be happy to eliminate all flights which
were less than 250nm, and I'd still handily meet the 500 hour requirement.
I pointed to a few of those transcontinental traversals. The inspector
smiled, and then we started discussing more important things, like where
the best scenery between X and Y was...)
> Examples:
> 1. VFR/IFR flight to an airport 35 miles away, touch-and-go, return to home
> base. Is this time loggable as X-country?
You can log it as cross-country if you wish, but you can't count that
cross-country time towards any advanced rating (possibly except the ATP).
So I'd say don't log it as cross-country. Simply, 35 < 50.
> 2. IFR flight to an airport 65 miles away, instrument approach, missed
> approach, return to home base. Is this time loggable as X-country?
No. You didn't land.
> 3. Is any missed approach countable for a X-country? How far into the
> approach do you have to get? Past FAF? To MDA? To DH/MAP?
You have to make physical contact with the runway. Landing is a fairly
explicit maneuver, and the word "landing" is what is used in the FARs.
That's when the rubber meets the road, er, runway.
Geoff
Mike Ciholas
>In article <BvM1K...@access.digex.com> step...@access.digex.com
>(John Stephens) asks about cross-country flight requirements:
>> 1. VFR/IFR flight to an airport 35 miles away, touch-and-go, return to
>> home base. Is this time loggable as X-country?
>You can log it as cross-country if you wish, but you can't count that
>cross-country time towards any advanced rating (possibly except the ATP).
>So I'd say don't log it as cross-country. Simply, 35 < 50.
I disagree. If the flight involved planning, weather, and navigation
then it is a cross country whether or not the airport of intended
landing is 49nm or 51nm from home base. The FARs say you need to have
cross country experience of a particular distance, that is more than
50nm, not that all x-countries are greater than 50nm.
>> 2. IFR flight to an airport 65 miles away, instrument approach, missed
>> approach, return to home base. Is this time loggable as X-country?
>No. You didn't land.
Again, I disagree. You cannot count it as cross country experience
for a rating, but it is cross country experience if you did the
planning, briefing, and navigating suitable for a cross country. I
have only one such experience, I flew from BED to nearly POU before
the weather became unfavorable. I turned around and returned to BED.
This was a 250nm round trip. Certainly you would believe me when I
say that this was every bit a cross country in the skills required for
navigation, weather judgement, and planning. I logged it as such. As
long as I don't claim this time as satisfying a rating, then I haven't
broken any FARs. I would even claim that the experience of such a
flight is why the FARs require cross country time.
>You have to make physical contact with the runway. Landing is a fairly
>explicit maneuver, and the word "landing" is what is used in the FARs.
>That's when the rubber meets the road, er, runway.
> Geoff
Where does the FARs define cross country? I agree that a flight with
a landing at an airport more than 50nm from point of departure is a
cross country in anyones book. But my definition would be:
Cross Country: Any flight in which the point of intended landing is
not the point of departure and planning for the flight included
weather and navigation.
The "landing" part is not the crucial phase of the cross country. The
planning is.
I guess my advice would be to use a consistent definition and to get
so much cross country time that it never is an issue.
Mike Ciholas
mi...@lcs.mit.edu
Richard Johnson
>Landing, as I understand, means that a tire squeaks; T&G counts; low or
>missed approach does not count.
>Lonnie C. Martin lon...@hydrogen.cchem.berkeley.edu
Now, I'm not gonna say this _actually happened_, but suppose you're on a
training flight, and your instructor pulls the carb heat and throttle, and
says, "engine out". Of course restart fails so you find this nice place
to land, and set up your approach (all the while thinking, the FAR's say
you're not supposed to get below 500' when you do this...), and flare for
a *soft* field landing.
He say's OK, go around. You GO really fast! You get back to the airport
and find dirt and a youung corn shoot on your left main.
Should you log it X-country? ;=)
--
Richard Johnson ric...@agora.rain.com
When you were born, you cried and the world rejoiced. Strive so that when
you leave this world, you rejoice and the world cries. --- Indian proverb
Jordan Brown
>If the flight involved planning, weather, and navigation
>then it is a cross country whether or not the airport of intended
>landing is 49nm or 51nm from home base. The FARs say you need to have
>cross country experience of a particular distance, that is more than
>50nm, not that all x-countries are greater than 50nm.
I believe we all agree that such flights require all of the skills involved
in cross-country flying. However, they are not acceptable flights to
count towards a rating, and therefore TO MAKE THE BOOKKEEPING EASIER Geoff
(and I, and most people I know) recommends that you do not log them as
cross-country.
>Where does the FARs define cross country?
They do not. They define what kinds of flights can be used for the various
requirements for ratings, and with the exception of the ATP rating those
requirements are quite specific. Unfortunately, they are also all
different, and none of them allow for the cases you mention. Welcome to
the FARs.
>I guess my advice would be to use a consistent definition and to get
>so much cross country time that it never is an issue.
I concur, and would recommend that the definition you use is that the flights
have a landing at a point more than 50nm from the point of origin, which
is sufficient for all of the requirements except for the few requiring
particular "long" flights. That way when you have to fill out the FAA form
for a rating you can look at your logbook and the "cross-country" column will
tell you the answer.
David Hightower
>As for the rest of the question, a landing not at the airport of origin
>makes the flight cross-country. The instructor I train with now argues that
>"cross-country" time should not include time spent in multiple approaches,
>or other practice that significantly extends the ATE. This seems
>reasonable, but I have not seen any clear reference in the FAR or AIM.
>Lonnie C. Martin lon...@hydrogen.cchem.berkeley.edu
We had a student pilot go up for his FAA checkride--he had 10.2 hours of solo X-country,
but the FAA examiner noticed that on his last flight he had logged 6 landings. What he had
done was to make the flight, then do some pattern work when he got back here. The examiner
figured that it took .5 to do those 4 "extra" landings, and disallowed the time; this meant
that the student only had 9.7 hours of solo X-country, and the examiner made him do one more
flight before he would give him his ticket.
_________________________________________________________________________
Dave Hightower | opinion? I'm allowed to have an opinion?
d...@cis.ufl.edu | well, if I DID have one, it'd be mine, all mine!
high...@cadre.af.mil | "Dum Vivimus, Vivamus!"
--------------------------------------------------------------------------
Steve Brecher
(John Stephens) asks
> What legally constitutes a cross-country flight?
>
> ... For the Private ticket, X-country flights must include a landing at an
> airport at least 50 miles away. For the IFR ticket, at least 50 hours of
> solo X-country time must have been logged, etc.
For the instrument rating, the requirement is 50 hours of cross-country as
pilot in command -- not necessarily solo.
> I can't find a clear, unqualified definition of X-country -- one that
> applies to logging time as X-country time after the Private or Instrument
> ratings have been obtained. Is there one? ... Do you have to
> actually LAND at a second airport ..., or does a missed approach (in IFR
> conditions) count?
For the (airplane) private and commercial certificates and for the
instrument rating, a certain amount of time is required on flights of more
than 50 nm with a landing (not just a missed approach) at an airport other
than that of origin. This is spelled out separately in each of the
experience requirements for the aforementioned certificates/rating. For
the ATP certificate, the nature of the required cross-country experience
is unspecified.
There is no definition of cross-country "in general," apart from the
requirements for the specific certificates and ratings. For the
cross-country column in one's logbook, there is no FAR analogous to 61.51
which specifies what may be entered in the PIC column.
In sum, prior to obtaining your commercial certificate and instrument
rating, you should keep a record of all your "more than 50 nm" flights.
Beyond that, the only "offical" reason to care about logging cross-country
is the ATP experience requirement. (Use caution, my own interpretation of
the FARs follows.) Since the nature of that requirement is unspecified,
any reasonable criterion may be used. E.g., a flight to another airport,
no matter what the distance, might be counted as cross-country; remaining
in the pattern at the original airport would not. However, for myself I
prefer to continue to log as cross-country only "more than 50 nm" flights
even though I have more than enough such flight time for the commercial
certificate, just to provide some uniformity to that column in my logbook.
--
bre...@pyramid.cs.unr.edu (Steve Brecher)
Bob Waldron
When I was building x-country time for my instrument rating I
understood the requirement was a flight greater than 50nm from
your point of origin plus a landing at that distant airport.
On one particular flight up to Laramie WY in my trusty KitFox
I discovered high and gusty winds at Laramie (almost always the
case). I circled the field several times watching the wind sock,
talked to unicom, even lined up on final but aborted the landing
due to nasty cross winds. Upon returning to Ft. Collins I told
my instructor of the non-landing, however, he said go ahead and
log that time as x-country.
His reasoning was that x-country flight are to get you away from
familiar surroundings, make you navigate, find and talk to un-
familiar airports, calculate fuel consumption, determine altitudes,
look up communication frequencies, (test your bladder ;-)), etc.
He said 'I know you can land the darn airplane, thats not the point
of a x-country'.
My advice is to use your own judgment when logging x-country or
any type of time in your log book.(familia ahe PIC discussions)
Your log book is an attempt to accurately represent YOUR EXPERIENCE
as a pilot and not just a 'water mark' check-off or a trophy to
show off all your time. You only cheat your self if you stretch
the truth when logging time. Also, if you fly a perfectly wonderful
and very technical 49nm x-country in which you gained valuable
experience you can in good a conscious call this a x-country.
Bob Waldron
bob.w...@ftcollins.ncr.com
Skip Guild
>
>When I was building x-country time for my instrument rating I
>understood the requirement was a flight greater than 50nm from
>your point of origin plus a landing at that distant airport.
>
>Upon returning to Ft. Collins I told
>my instructor of the non-landing, however, he said go ahead and
>log that time as x-country.
>
>and very technical 49nm x-country in which you gained valuable
>experience you can in good a conscious call this a x-country.
Agree with first part but the second can lead to problems with some
examiners who know the distance between certain airport pairs that
are close to but are not cross country and disqualify these entries.
Be sure you have the required times and distances without counting any
"questionable" trips. Far 61.65(e)(1) calls for 50 hours of cross
country with "landings at a point more than 50 nautical miles from
the original departure point." No one but you and your safety pilot
knows how many squeeks were heard on the "landing". Let your
conscience and FAR 61.59 be your guide.
If you have 55 hours of such cross country time logged and one is a
questionable 49 mile flight, the examiner might "discount" it but you
would still have over 50 hours with the remaining flights.
Besides, you can use some of your hood time (without expensive
instructor but with a safety pilot) to work on cross country navigation
and shoot approaches at those 55 mile distant airports logging both
hood and cross country time. Kill two birds with one stone, as they
say.
Jordan Brown
>My advice is to use your own judgment when logging x-country or
>any type of time in your log book.
While I agree that a 49-mile trip or a >50-mile trip that didn't include
a landing at the far end can be valuable XC experience, the FAA _will_
go by the exact FAR definitions if they decide to check up on your
experience, and so you should be careful that when you fill out an
FAA form, a ratings application for instance, that you count only those
hours that meet the FAR requirements for the rating you are pursuing.
This is easiest if you log as XC only those flights that meet the FAR
requirements. I would suggest using the landing >50 rule.
The fact that you don't log the 49-mile flight as XC, or don't log the
100-mile no-landing flight as XC, doesn't erase that experience from your
brain, which is the _really_ important part. If, on the other hand,
you log a 49-mile flight as an XC and the FAA examiner notices it,
it _will_ be disallowed and if this takes you below the required number
of hours you will get a pink slip, and your instructor might get in
trouble for recommending a candidate who does not meet the requirements,
and in general you will be unhappy. Note that the examiner for your home
airport will almost certainly know which airports are more than 50 nm from
it...
Dave Allen
and how close the wheels need to come to pavement to log cross country time.
My signature came from a similar thread some time (year(s)) ago. Here is
the original, uncut ...
dave allen - Fly because you love it - not to log it.
200 Klaus Kraemer
>bo...@ncr-fc.ftcollins.NCR.COM (Bob Waldron) writes:
>>My advice is to use your own judgment when logging x-country or
>>any type of time in your log book.
>
>100-mile no-landing flight as XC, doesn't erase that experience from your
>brain, which is the _really_ important part.
That's really the key point. Many times in how-do-I-log-this
discussions, the terms currency and proficiency are mixed up.
Currency means legality, which is quite narrowly defined. Proficiency
cannot be measured in absolute terms; but that is what keeps you
alive.
Remember that you are the one who signs the logbook to be correct.
If you want to remember the no-landing XC flight in later times, put
a note in. (You can learn how to scribble in very small writing. Ask
an instructor; these guys put up to four lines on one printed line.)
Then you will be not the only one who knows that your XC flight
many months ago did not have a landing... ;-)
Klaus.
Phil Fernandez
>100-mile no-landing flight as XC, doesn't erase that experience from your
>brain, which is the _really_ important part. If, on the other hand,
>you log a 49-mile flight as an XC and the FAA examiner notices it,
>it _will_ be disallowed and if this takes you below the required number
>of hours you will get a pink slip, and your instructor might get in
>trouble for recommending a candidate who does not meet the requirements,
>and in general you will be unhappy. Note that the examiner for your home
>airport will almost certainly know which airports are more than 50 nm from
>it...
A perfect case in point is Palo Alto (PAO) to Stockton (SCK). The two
airports are 49 miles apart. This is a disappointment to some
instrument students flying out of PAO, since SCK is a very popular
practice ground for approaches. If SCK were one mile further, it
would be very tempting to add a landing and some cross country time
after doing practice approaches.
This wasn't a problem for me, since I had lots of X-C time, but I've
heard CFIs around West Valley advise that DEs that work at PAO keep a
close eye on PAO->SCK time logged as X-C.
pmf
pp-asmel-ia
mooney n5632j
Geoff Peck
> [What are] the requirements for dual cross country prior to solos.
There are no mileage or time requirements for dual cross-country flights
prior to solo. If an instructor deemed it appropriate, a flight to an
airport 10nm away from the point of origin could be counted as a dual
cross-country flight. The key here is that the instructor determines what
is a cross-country and what is not.
The criteria I use when conducting such a flight with one of my students
include:
(1) written flight planning must be done
(2) a VFR flight plan must be filed for at least part of the flight
(3) the flight must be long enough and over sufficiently unfamiliar
country that navigational skills are exercised -- preferably a
combination of dead reckoning, pilotage, and electronic navigation
(4) the flight must land at an unfamiliar airport or airports
(5) the flight should contain things of additional educational
value, if at all possible (e.g., flight following, filing a
PIREP, flying through a TCA, etc.)
Geoff
Lonnie C. Martin
>While I agree that a 49-mile trip or a >50-mile trip that didn't include
>a landing at the far end can be valuable XC experience, the FAA _will_
>go by the exact FAR definitions if they decide to check up on your
>experience, and so you should be careful that when you fill out an
>FAA form, a ratings application for instance, that you count only those
>hours that meet the FAR requirements for the rating you are pursuing.
>
>This is easiest if you log as XC only those flights that meet the FAR
>requirements. I would suggest using the landing >50 rule.
>
>The fact that you don't log the 49-mile flight as XC, or don't log the
>100-mile no-landing flight as XC, doesn't erase that experience from your
>brain, which is the _really_ important part. If, on the other hand,
>you log a 49-mile flight as an XC and the FAA examiner notices it,
>it _will_ be disallowed and if this takes you below the required number
>of hours you will get a pink slip, and your instructor might get in
These are excellent points, well put on this topic. I would add that one
_can_ log flights with landings at an airport other than the point of
departure not more than 50 nm as cross-country, with only one reservation,
they cannot be used to satisfy the cross-country experience requirements for
the private, instrument, and commercial tickets. That being the case, it is
probably a good idea to make some sort of logbook notation for flights that
are to be counted toward a particular ticket. Like maybe an asterisk for x-c
flights > 50 nm. Just a thought.
Lonnie
that those flights not more than 50 nm
Lonnie C. Martin
...
>A perfect case in point is Palo Alto (PAO) to Stockton (SCK). The two
>airports are 49 miles apart. This is a disappointment to some
>instrument students flying out of PAO, since SCK is a very popular
>practice ground for approaches. If SCK were one mile further, it
SCK would have to be _2_ miles further from PAO to satisfy the > 50 nm
requirement.
Lonnie
Lonnie C. Martin
>>2 hours is required. Which brings me to my point. Kalamazoo is just less
>than 50 nm from South Bend, and is popular as a training flight destination
>because it has a TRSA (or whatever the new name is). Would a dual flight to
>such a place be loggable as cross-country from the point of view of satisfying
>the requirement for solo cross countries?
...
I don't see how dual instruction could be counted as solo time (or PIC) for
a student pilot. For PP or greater - seems like it could, as long as all
other requirements for logging the X-C (or other) flight as PIC are met.
(as I recall ... FAR 61 not in front of me)
Gerald Radack
>In article <1992Oct15.0...@xymox.palo-alto.ca.us> ph...@xymox.palo-alto.ca.us (Phil Fernandez) writes:
>...
>>A perfect case in point is Palo Alto (PAO) to Stockton (SCK). The two
>>airports are 49 miles apart. This is a disappointment to some
>>instrument students flying out of PAO, since SCK is a very popular
>>practice ground for approaches. If SCK were one mile further, it
>...
>SCK would have to be _2_ miles further from PAO to satisfy the > 50 nm
>requirement.
>
you take out your sectional chart and find that two airports are 50+delta miles
apart. How do you know that they are really far enough apart, since there
will be errors in the map's projection, the plotter dimensions, etc. Also,
how do you know you placed the ends of the plotter on the proper places on
the airport? Does the FAA publish an official algorithm for determining the
distance between two points? I am pretty sure that they do not mean straight-
line distance, since that would go through the earth. Somebody is probably
going to say "great circle distance, of course", but at what altitude?
What happens if there are mountains between the airports? Do you include the
extra distance needed to climb and descend? What happens if the airports are
at different altitudes?
Inquiring minds want to know.
--
Gerry Radack
EEAP (216)368-2808
Case Western Reserve University rad...@alpha.ces.cwru.edu
Cleveland, OH 44106
200 Klaus Kraemer
Let me add one: What if you're IFR and the outer marker is more than 50
NM from your starting point? Then you _have_ to fly at least that far.
Geoff Peck
The great-circle distance from ARP to ARP (airport reference point) is
what counts. You can obtain this distance by measuring on a sectional
between the centers of the airport symbols.
If this isn't precise enough for you, the easiest thing is to ask the
Contel DUATS flight planner. It has an online database of all of the
airports in the Continental U.S., and it knows how to compute great-circle
distance between the origin and destination.
If you want to do it yourself, the raw numbers for ARP's may be found in
the Airport/Facility Directory, and the following formula:
distance = acos(sin(a.lat) * sin(b.lat) +
cos(a.lat) * cos(b.lat) * cos(b.lon - a.lon)) * 60.
which comes from the application program manual which came with the
HP25 calculator, pp. 72-74.
Geoff
Geoff Peck
(Klaus Kraemer) writes:
[33 lines of excessive quoting deleted -- folks, PLEASE TRIM YOUR QUOTES]
> Let me add one: What if you're IFR and the outer marker is more than 50
> NM from your starting point? Then you _have_ to fly at least that far.
Nope. It's airport center to airport center. That's the way it's
defined. The route you take, direct or circuitous, has no bearing on
whether or not a flight qualifies as cross-country with respect to
pilot experience for the various ratings in question. Go read the
FARs. It's straight line, airport to airport. No ifs ands or buts.
Geoff
Gary Moore
I disagree that measureing the distance between two points on a sectional
will give you the shortest distance. Sectional charts are a perculiar
form of map know as Lambert Comformal Conic Projection. What this means
to pilots is open for discussion, however - on sectional charts the lines
of longitude are parallel, not so in real life. Drawing a line between
two points on the sectional yeilds something call the Rhumb Line course
and is NOT the shortest distance. Now admittily, for most of us, it is
close enough to use and not worry about the difference.
Great Circle routes ARE the shortest distance. The GSR is defined by the
arc made by the intersection of a plane formed by the two points in
question and the center of the earth. It can be calculated, but is
difficult to measure.
There are large differences between GSR and Rhumb line on trips of large
distances. You won't find Intercontinental flight flying Rhumb Lines.
--
The opinions expressed are not necessarily those of the University of
North Carolina at Chapel Hill, the Campus Office for Information
Technology, or the Experimental Bulletin Board Service.
internet: bbs.oit.unc.edu or 152.2.22.80
Ron Natalie
> What this means
> to pilots is open for discussion, however - on sectional charts the lines
> of longitude are parallel,
This is untrue. On the Sectionals (which are as stated, Lambert Conformal
Conic Projections), the latitude and longitude lines are NOT parallel.
The longitude lines are slightly closer at the top then at the bottom and
the latitude lines are not even straight, they are arcs (very gradual ones
on sectional).
The Lambert Conformal provides very low distortion in angles and in distance
over the 600 miles or so that a sectional covers, and certainly negligable
error in the 50 miles were talking about to see if we can use this airport
for the instrument cross-country requirement.
You might as well have mentioned the errors involved because the earth is
not a sphere and the effect of the differences in altidude between the
two airports.
-Ron (I do this for a living) Natalie
Nobody talks about rhumb lines much except when they have mercator projections
(where the meridians are parallel).
Kerry Kurasaki
>
>I disagree that measureing the distance between two points on a sectional
>
>Great Circle routes ARE the shortest distance. The GSR is defined by the
>arc made by the intersection of a plane formed by the two points in
>question and the center of the earth. It can be calculated, but is
>difficult to measure.
>
Great circle plotting is impractical in 'normal' GA flying. With the
complexities of airspace restrictions and terrain, it is almost
impossible to fly. Some examples:
An MOA in the way where diverting 5 or 10 miles is worth the time.
A mountain peak in the way. Hmmmm, I should probably go around it.
If I add an extra 10 miles to my 300 mile trip, I can stay over
roads and/or hospitable terrain.
Lack of electronic navaids. Not everyone has LORAN or GPS.
Fuel is $.35/gal cheaper at this airport 20 miles [slightly] off
course. I'll make the diversion.
Food is better at the restaurant at the airport 35 miles off course.
I really need a $100 buffalo burger today!
Sectional plotting for students is still an easy to teach and practical
way to navigate. If your student drives a G-IV, then just type the
coordinates into the VLF/Omega and go along for the ride.
Kerry
Lars-Henrik Eriksson
In article <1992Oct23....@samba.oit.unc.edu> Gary....@bbs.oit.unc.edu (Gary Moore) writes:
>
> There are large differences between GSR and Rhumb line on trips of large
> distances. You won't find Intercontinental flight flying Rhumb Lines.
And funny enough, you won't find intercontinental flights flying exact GSR's
either: ...
So what must be done on long flights is an approximation of a GSR with
(arbitrary short) sections of constant heading.
On intercontinental flights, particularly at jet altitudes, you don't
want to fly either a GSR or a RL. You want to fly a route that is
optimal in time or fuel consumption considering the current weather
patterns!
E.g. if your planned route takes you through the centre of a low
pressure area, it could well be advantageous to make a detour on the
right side of the low (assuming you are on the northern hemisphere) to
take advantage of the tailwinds.
An example of this is the North Atlantic Track Structure, the
"airways" between Europe and North America. Each of these "airways"
begin and end at fixed points near the respective continents, but
instead of being great circle tracks between those points, they are
changed every 12 hours to take advantage of the weather patterns.
I read somewhere about a "isobar navigation" - a method for
intercontinental navigation that was used when traffic over the oceans
were still light enough that separation was not a factor. The aircraft
were equipped with a long-range radar altimeter and flew so that the
difference between radar altitude and pressure altitude was always the
same. If the radar altitude increases, turn left, if it decreases,
turn right.
In this way the aircraft would fly along the isobar and always have a
straight tailwind (presuming it flies on the right sides of the low-
and high pressure areas.)
--
Lars-Henrik Eriksson Internet: l...@sics.se
Swedish Institute of Computer Science Phone (intn'l): +46 8 752 15 09
Box 1263 Telefon (nat'l): 08 - 752 15 09
S-164 28 KISTA, SWEDEN Fax: +46 8 751 72 30
Lonnie C. Martin
country is greater than 50 nm, is on the PP, CP, and Instrument checkrides.
Somehow, I suspect that the issue will be resolved with a plotter and
sectional chart - by the DE or inspector performing the practical test.
I don't know from experience, but doubt that any of the other methods would
be used to resolve the question. Furthermore, challenging the person giving
the test, while perhaps occasionally acceptable, has been, in my experience,
not a very good idea. It might lead to "examinee error" further along in the
practical test, if the examiner were so inclined. On the other hand, the
examiner might be pretty impressed. --- but I doubt it. :-)
How much difference in a 50 nm example is there, between measuring on the
sectional and measuring the great circle distance?
Dick Harrigill
>will give you the shortest distance.
Since this thread has been talking about the 50nm distance for a
minimum XC, and the majority of use are probably somewhere around
45 degrees N (give or take a few), then we must measure not at least
50nm on our sectionals, but 50nm plus about 15 feet! :-)
If you can measure that on your sectional, you have much better
eyes and equipment than I.
If you are using a great circle in normal GA flight planning, don't
bother. The Great Circle is fine for long distances, but for GA it is
useless for anything except finding a general route for a very long flight.
Your individual flight legs are still going to be figured in direct
sectionally measured distances. If you have a flight leg long enough
for it to matter, you certainly have a better aircraft and navigation
equipment that the rest of the GA world.
For example, fly the great cirlce from Seattle to London. You will
cross over Hudson Bay, Greenland, Iceland... (approximately).
What will be your heading? It will change in route, and your heading
will be a function of your position. In this example you will start
with a NE heading, which will slowly turn to E, then SE. Try to
show that on a flight plan! What you will do is break the flight
up into small chunks, each with a discrete heading and distance.
--
Dick Harrigill, an independent voice from: Boeing Commercial Airplanes
M/S 9R-49 PO BOX 3707 Renton Avionics/Flight Systems
Seattle, WA 91824 Computing Support
(206) 393-9539 rfh...@galileo.rtn.ca.boeing.com CDP, PP-ASEL
David Lesher
I must admit my disappointment. Sure, GSR routes mean constantly
changing headings. So what? We've got all these great computers to
carry wreck.aviation around the world. A small fractions of the cpu and
memory cycles spent on, oh say, PIC logging squabbles would do the
job. All we have to do is turn our Sparcs into autopilots...
Clearly it's just another SMOP.
SMOP = Simple Matter of Programming. Typically evoked by hardware types
during project arguem^H^H^H^H meetings.
;-}
;-}
--
A host is a host from coast to coast..wb8foz@skybridge.scl.cwru.edu
& no one will talk to a host that's close..........................
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
Chris Best
> sectional and measuring the great circle distance?
----------
On the order of feet, I'd guess.
Jeffrey Dunkle
country....here's andother $.02.
We have a very good X-C destination nearby.....Johnstown, PA...JST.
Plateau in the Pa. hills...excellent restaurant...several instrument
approaches...and a recently added tower with very friendly personnel.
From one popular airport with lots of student activity...its 49.4 nm
away...but if you add a little parallax to the plotter....some folks
take the 50 nm credit.
Fortunately, I didn't. The examiner for my instrument check ride only
checked two features of my log book during our "session".....my PIC/X-C
entries for "legitimacy"...and my instructor's notes on my instrument
cross country.
As the president of a flying club with about 8 currently active
instrument students and several members with fresh privates....I
encourage them ALL to go as quickly as funds and interest allow for
their instrument ratings. Anyone who is in a position to know, like me
as a club officer, CFII's etc., owe it to instrument students to assure
that they get their 50 hours PIC/X-C legitimately.
Beyond that....whether the distance to a claimed cross country
destination is 15 feet more or less if polar, rhombic, mercator
projection, great circle, Lorentz transformation, or other geometric
system is used, is sort of moot.
Didn't mean this to sound like I'm flaming on the interesting
dialog.....just want to remind us what one "purpose" of draining this
swamp was.
Jeff D.
Berry Kercheval
> How much difference in a 50 nm example is there, between measuring on the
> sectional and measuring the great circle distance?
Chris> On the order of feet, I'd guess.
I'd say that certainly it is less than the error in your measuring
instruments. Did you know that temperature and humidity variations
can make your char bigger or smaller? It does, but it's not
measurable with a typical plotter. For typical GA flights, routing
around obstacles, mountains, TCAs and the like far outweigh getting an
GC route 100 feet shorter. Maneuvering in the patter will eat up the
time saved (which, at 100 knots, is less than a second).
All this nattering about how to measure the distance between two
airports strikes me as pointless. If you can't decide if a particular
flight is 49.9 or 50.1 nm, just don't log it as XC. Sheesh; it's only
.5 hours. If you're going for a rating and a half hour of logged time
makes the difference, just go and fly somewhere and back before the
checkride.
--berry
--
Berry Kercheval :: be...@pei.com :: Protocol Engines, Inc. Mt. View, CA
Dan Arias
logbook entries by referring to a sectional chart that had
a 50nm circle drawn around my home airport with a compass
(the pointy/pencilly kind). Airports either fell inside,
on, or outside the line. Guess which ones counted?
For the checkride, I was told to make sure all the docs
were on the plane and to pull the airframe, prop, and engine
logs and make sure they were current. I also wanted my logbook
to be squeaky clean with no doubts as to what the entries
meant. Doing these things seemed to put the DE at ease,
giving him a certain confidence in my abilities (at least
my ability to be neat). This same at-ease, confident-that-
I-could-be-neat DE was later to find things during the flight
test that migitated his feeling somewhat, but by then, it was too
little too late so he passed me anyway.
As far as I can tell, the next time someone will care about
how I log my x-c's will be the examiner for my Instrument
checkride.
Maybe the DE's out in the audience should let us know what
it is about logbook x-c entries that gives them warm-fuzzies,
and inspires confidence in the candidate's abilities to operate
powerful and complex machines at dizzying heights through
storm-tossed skies, in murky clouds, or the gloom of night.
``What do you mean, I can't shoot my own men?''
--Gen Dreedle, Catch-22
--Dan
Matthew Waugh
>All this nattering about how to measure the distance between two
>airports strikes me as pointless.
Pointless, pointless? Are you kidding me? It's given me excuses for
being lost for at least the next 10 years.
"It was the humidity, made the chart swell, so of course I landed
short of the airport."
"It was cold this morning, so my plotter shrank, that's why I never
found that flagpole checkpoint."
"I would have been back on time, but the rotation of the earth caused
me to fly past the airport."
No, no, this is great stuff. I thought I was just incompetent, but I
see now what the problem is.
Mat
:-) It was supposed to be funny.....
Matthew Waugh wa...@dg-rtp.dg.com
RTP Network Services
Data General Corp.
RTP, NC. (919)-248-6034
24224-guthrie
>Pointless, pointless? Are you kidding me? It's given me excuses for
>being lost for at least the next 10 years.
>
>"It was the humidity, made the chart swell, so of course I landed
>short of the airport."
>"It was cold this morning, so my plotter shrank, that's why I never
>found that flagpole checkpoint."
>"I would have been back on time, but the rotation of the earth caused
>me to fly past the airport."
You still need excuses? Hell, I've turned getting lost into an art form.
I think my masterpiece was ending up in Wilmington, Delaware on a flight
from Clarksburg, West Virginia to Manville, New Jersey. It *was* a dark
night!
pat...@dasher.cc.bellcore.com
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| To get the attention of a large animal, be it an
| elephant or a bureaucracy, it helps to know what
George Patterson - | part of it feels pain. Be very sure, though, that
| you want its full attention.
| Kelvin Throop
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