fly over vs fly by fix

[tathepilot]

lets say your route is v16 jfk frg.

by how much of a lead could you legally turn towards frg before hitting jfk vor?

thx

 

[nosehair]

4 nm. The width of the airway.

 

[AC560]

Good explanation in AIM 5.3.5

 

[tathepilot]

Good explanation in AIM 5.3.5

yes im aware of 5.3.5 and 91.181....
and this makes sense, but i was looking for more specifics as to the amount of lead..

so a lead would be ok if you were within 4nm of the centerline...?

im asking this because i got a phone call yesterday, about loss of separation (not a good call)
this flight took place 2 months ago and it confuses the *hit out of me because initially 'they' believed it was an 'operational mistake on their part', but i guess someone is looking to point a finger

-----------------------------------------------
also, im aware of fly-by vs fly-over fix's on terminal procedures.., you know the fix that is circled.
are there such 'fly-over' fixes on low altitude charts?

 

[AC560]

but i was looking for more specifics as to the amount of lead..

They give you a picture and an example of why & how you would calculate the lead as well as clarify how it remains compliant with 91.181, not sure what more specific there is (perhaps I don't understand the question you are trying to ask)?

5-3-5. Airway or Route Course Changes
a. Pilots of aircraft are required to adhere to airways or routes being flown. Special attention must be given to this requirement during course changes. Each course change consists of variables that make the technique applicable in each case a matter only the pilot can resolve. Some variables which must be considered are turn radius, wind effect, airspeed, degree of turn, and cockpit instrumentation. An early turn, as illustrated below, is one method of adhering to airways or routes. The use of any available cockpit instrumentation, such as Distance Measuring Equipment, may be used by the pilot to lead the turn when making course changes. This is consistent with the intent of 14 CFR Section 91.181, which requires pilots to operate along the centerline of an airway and along the direct course between navigational aids or fixes.
b. Turns which begin at or after fix passage may exceed airway or route boundaries. FIG 5-3-1 contains an example flight track depicting this, together with an example of an early turn.
c. Without such actions as leading a turn, aircraft operating in excess of 290 knots true air speed (TAS) can exceed the normal airway or route boundaries depending on the amount of course change required, wind direction and velocity, the character of the turn fix (DME, overhead navigation aid, or intersection), and the pilot's technique in making a course change. For example, a flight operating at 17,000 feet MSL with a TAS of 400 knots, a 25 degree bank, and a course change of more than 40 degrees would exceed the width of the airway or route; i.e., 4 nautical miles each side of centerline. However, in the airspace below 18,000 feet MSL, operations in excess of 290 knots TAS are not prevalent and the provision of additional IFR separation in all course change situations for the occasional aircraft making a turn in excess of 290 knots TAS creates an unacceptable waste of airspace and imposes a penalty upon the preponderance of traffic which operate at low speeds. Consequently, the FAA expects pilots to lead turns and take other actions they consider necessary during course changes to adhere as closely as possible to the airways or route being flown.

 

[Flythis]

flyover

turn you must

 

[tathepilot]

turn you must

sentence

1. A grammatical unit that is syntactically independent and has a subject that is expressed or, as in imperative sentences, understood and a predicate that contains at least one finite verb.

 

[JediNein]

What altitude, equipment suffix, airspeed, and type aircraft (piston multi, slowtation, BXXX)?

And if you were just advised of the 'possible' deviation, have you filed a NASA report or equivalent? One successful defense against a violation sanction occurred because ATC didn't notify the flight crew of a 'possible' deviation. Thus the crew didn't file reports and were unable to attain the certificate protection available. I don't recall if the NTSB board threw out the entire case or just the sanction.

Good luck!

 

[midlifeflyer]

I once came across a technical formula based on speed and the radius of the turn but I think it eventually came down to something like

No of degrees to turn/3 x GS/3600

assuming a standard rate turn.

I just use the same 10% of groundspeed rule of thumb that is generally used for the 90° turn to intercept a DME arc, realizing that if the turn in less than 90° I can use something less and if greater than 90° something more

 

[tathepilot]

What altitude, equipment suffix, airspeed, and type aircraft (piston multi, slowtation, BXXX)?

And if you were just advised of the 'possible' deviation, have you filed a NASA report or equivalent? One successful defense against a violation sanction occurred because ATC didn't notify the flight crew of a 'possible' deviation. Thus the crew didn't file reports and were unable to attain the certificate protection available. I don't recall if the NTSB board threw out the entire case or just the sanction.

Good luck!

no nasa.. made aware of this 1.5 months after the fact.
c210t/u, 180kts @ 040