PDA

View Full Version : Offpath Descents


DBEnterprises
4th Mar 2002, 04:33
G'day all,. .. .Only new to the game but..... .. .Can anyone provide me information/background knowledge of "Offpath Descents" (What are they?, How are they programmed? etc...). .. .I would appreciate anything.. .. .Thanks in advance.. .. .DT..

Herc Jerk
4th Mar 2002, 09:11
IMHGuess, it would depend on what you are programming. if it is the 1900AD series human brain on an IFR descent to LSALT you would need to re work it to allow for your change of track to ensure you don't smack into something solid.. .. .does that help/sound right? probably not.. <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" /> . .. .HJ

Checkboard
4th Mar 2002, 09:20
If you fly with a reasonably sophisticated GPS or Flight Management System, then you can usde the system to plan your vertical path during (usually) the descent. If you have to deviate from that plan - usually because of an ATC instruction, then you are off the planned path, called an "offpath" descent.. .. .On the Boeing FMS you define your vertical path with the various vertical points you whish to be at, and then select either PATH descent or SPEED descent. In the path mode the aricraft pitches up and down to follow the plan, and your speed will vary, according to the accuracy of the winds you have told the FMS to expect on the way down. In the speed mode, the aircraft will follow the planned descent speed, and you may drift off the path - the drift will be displayed on a path indicator in a glass cockpit.

Fresca
8th Mar 2002, 23:56
Well Checkboard!. .On the Pegasus equipped 757's there is a feature called offpath descent. I've never used it myself, but it works by one enters a point or a fix on the page, and the altitude one whises to be over that point/fix. Then the FMC shows two circles around that point, one circle where one must start the descent in clean configuration to reach that point at that predeterment altitude, and the other circle (in different color, don't remember what) inside the other one, where one must start the descent with the speedbrakes fully extended.. .Hope it helps.. .Fresca

Pegasus77
9th Mar 2002, 00:47
I been equipped on a 757? <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" /> <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" />