DME v height practice profile from high altitude
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DME v height practice profile from high altitude
In another era, one of the first things I learned about flying a descent was the DME versus height profile applicable to the aircraft type. It took good instrument flying skill to maintain the appropriate speed applicable to each segment of the profile.
In event of an unexpected change by ATC (shortening or extending distance to run), and either the FMC unavailable or the pilot losing the plot because of slowness in button pressing, the ability to seamlessly switch to DME v height meant good situational awareness, and was a handy skill to fall back on. I am surprised that this skill is not encouraged during type rating or recurrent simulator training. And it is a skill; especially when winds are factored in and you are descending from high altitudes.
To aid the pilot it was common practice to ask ATC for the distance to run to touch-down since the controller should know which runway is likely and what other aircraft are around whose presence could affect your planned profile.
The trap of automation dependency is well known but from what I see and hear, few operators take it seriously or introduce effective measures to fix the problem. Different operators - different priorities for simulator training - are a fact of life nowadays. For new pilots on type, time spent in the simulator on high altitude descent profiles (preferably manually flown) is well worth the time used to teach energy (speed v height) control right from the start. Comments invited
In event of an unexpected change by ATC (shortening or extending distance to run), and either the FMC unavailable or the pilot losing the plot because of slowness in button pressing, the ability to seamlessly switch to DME v height meant good situational awareness, and was a handy skill to fall back on. I am surprised that this skill is not encouraged during type rating or recurrent simulator training. And it is a skill; especially when winds are factored in and you are descending from high altitudes.
To aid the pilot it was common practice to ask ATC for the distance to run to touch-down since the controller should know which runway is likely and what other aircraft are around whose presence could affect your planned profile.
The trap of automation dependency is well known but from what I see and hear, few operators take it seriously or introduce effective measures to fix the problem. Different operators - different priorities for simulator training - are a fact of life nowadays. For new pilots on type, time spent in the simulator on high altitude descent profiles (preferably manually flown) is well worth the time used to teach energy (speed v height) control right from the start. Comments invited
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For new pilots on type, time spent in the simulator on high altitude descent profiles is well worth the time used to teach energy control right from the start.
Why the sim? That is considered valuable time and not to be wasted on trivia. Why not in real life? However, there are some operators that insist on VNAV as default and at all times have a path active.
I used to see guys following a complicated STAR in LNAV & VNAV. OK. Then ATC vector you to a corner cut. The first thing they ask for is the FMC update and do nothing. After some seconds the VNAV says you are high. Shock horror; what a surprise. Then it is speed up and speed brake and a nervous twitch. The discussion then follows the lines of, "would it have been a good idea to go LVLCHG and accelerate while PM was fiddling with the FMC; then perhaps the 'high deviation' would have been less, even zero?"
I also read reports from Flt Ops warning guys who had became too high at the FAF or G.S intercept and later made a GA. The warning was about accepting ATC short cuts to finals. A tailwind at FL100 with a head wind on ground is a real gotcha. But why should Flt Ops need to warn crews of this danger? That is what the two pilots are there for. If you have SA you do not have to accept an ATC offer; it is just that. You are the manager of the energy state of the a/c; so manage it.
Why the sim? That is considered valuable time and not to be wasted on trivia. Why not in real life? However, there are some operators that insist on VNAV as default and at all times have a path active.
I used to see guys following a complicated STAR in LNAV & VNAV. OK. Then ATC vector you to a corner cut. The first thing they ask for is the FMC update and do nothing. After some seconds the VNAV says you are high. Shock horror; what a surprise. Then it is speed up and speed brake and a nervous twitch. The discussion then follows the lines of, "would it have been a good idea to go LVLCHG and accelerate while PM was fiddling with the FMC; then perhaps the 'high deviation' would have been less, even zero?"
I also read reports from Flt Ops warning guys who had became too high at the FAF or G.S intercept and later made a GA. The warning was about accepting ATC short cuts to finals. A tailwind at FL100 with a head wind on ground is a real gotcha. But why should Flt Ops need to warn crews of this danger? That is what the two pilots are there for. If you have SA you do not have to accept an ATC offer; it is just that. You are the manager of the energy state of the a/c; so manage it.
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DME/Best (worse) case track miles vs height (or achievable FPA) has to be considered for every descent. We are very lucky in so much that we are regularly fflying to destinations with pathetic ATC that we have become accustomed to playing to playing the system. But we can only be players if we know what we can do, hence the understanding between height and distance. Having said that I only ever recall one sim detail where we had the "bum's rush" in a descent. Fortunately, we are not forced to use VNAV; a system designed to create either unstable or uneconomic approaches - ATC never stick to your plans.
Last edited by Piltdown Man; 12th Feb 2017 at 10:41.
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I would nearly argue that the magenta line syndrome is more prominent in the vertical than lateral sense. I have annoyingly often flown with guys (and girls) sitting on both sides of the aeroplane who seem almost entirely unable to decipher when VNAV is telling them or doing something stupid. I have seen high speed level change with speedbrake over 120 miles out because VNAV says we are 9999' high only to spend 5+ minutes with v/s 100' trying to avoid a level segment later on. Likewise I have more than once seen a request for more track miles (or very hurried and uncomfortable descents) despite no adverse winds or shortcuts simply because VNAV says on profile and the flying pilot believes it over 3x tables.
Despite not being in this industry for long, and firmly being in the magenta generation myself, I consider myself lucky to have been forced to do things myself through flying ill-equipped aircraft and having had 'oldschool' instructors once flying better equipped ones. Not to say I always get it right of course!
Despite not being in this industry for long, and firmly being in the magenta generation myself, I consider myself lucky to have been forced to do things myself through flying ill-equipped aircraft and having had 'oldschool' instructors once flying better equipped ones. Not to say I always get it right of course!
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When ever an opportunity presents itself to demonstrate that VNAV is not the all-wise guru that some think it is I grasp it fervently. It is an eye opener. There was often one place where we are on the ILS GP from many >20 miles out and yet the VNAV says we are 00's low. I point this out and ask what the youngster thinks. What should he do? There is much confusion. Why, how, what? I don't understand.
Well, look at the GP, the height & DME. Are they correct? Yes. Good. Then as we approach the OM the GP & VNAV merge accurately.
Bring your answer to school tomorrow and we'll discuss it. No matter, it has shown that the best computer in the a/c is between your ears. Never forget it. But then again, it has to have downloaded the Piloting APP first.
Well, look at the GP, the height & DME. Are they correct? Yes. Good. Then as we approach the OM the GP & VNAV merge accurately.
Bring your answer to school tomorrow and we'll discuss it. No matter, it has shown that the best computer in the a/c is between your ears. Never forget it. But then again, it has to have downloaded the Piloting APP first.
