I was just wondering, when a pilot files a High Altitude (Jet) flight plan for J tracks above FL 180, are they strictly enforced so that one can't fly let's say at FL 150? In other words, can you be on a J airway below 18000 or a Victor airway above? Thanks. Regards, Tom

Hi, if you compare high and low enroute charts you

VORs used with low altitude airways may not have enough range suitable for use on the longer legs of high altitude airways. Those that are indicated on high altitude airways may be used on both.The high altitude airways exist to give longer direct routes for generally higher performance aircraft. It is prohibited for VFR flight from FL180 and above so you have the advantage of having all aircraft (legally) under IFR control rules to maintain seperation. The FL180 up transition level to this Class A all controlled airspace may be different in jurisdictional areas of countries outside the US.For filing a plan you would not use a J airway below FL180 but would either have a common transition point to a low altitude V route or file direct to a point where you could pick one up.Note that there are less waypoints and intersections on the high altitude airways which are meant for high speed more direct routing with longer distances between waypoints without (theoreticly) having the inconvenience of avoiding VFR aircraft not being under ATC.

You are asking about a highly artificial situation. A pilot filing a high altitude flight plan (say for a jet) isn't going to like to cruise at 15,000 ft. So it ain't going to happen ... Michael J.WinXP-Home SP2,AMD64 3500+,Abit AV8,Radeon X800Pro,36GB Raptor,1GB PC3200,Audigy 2, Omega 2.7.90 (4xAA 16xAF)