01-10-2009, 08:38 AM
Schiphol airport (EHAM) has done tests using this technique 10-15 years ago (maybe even longer). The ieda was to come in at higher
altitude that is custom today (say 4000-5000 ft) and then come in at very low power settings. This would reduce noise levels drastically
(no-one cared about fuel that much these days).
The tests were successful in the sense that it could be done, but apparently the flying skills required, the fact that different approach
procerures should be used depending on the weather conditions (you do get a steeper descent rate whick is not desirable in low visibility
conditions) and the wind-up time for the engines to go from idle or very low power settings to TOGA (making go around a potentially risky
affair, especially because of the steeper descent) caused the idea to be abandoned. So this is a very old idea indeed. Maybe new
technology has taken away some of the downsides, but definitely not all I would imagine.
And if this is used as standard procedure today (UPS?), how would that work? Only with visual approach I gather, because there's no way
you can stay on the ILS glidepath with your engines idled. The Turkish airlines crash near EHAM proved that more than sufficiently! And
would ATC allow you to deviate from the normal approach procedure? Again, I think not (at least not on busy airports).
altitude that is custom today (say 4000-5000 ft) and then come in at very low power settings. This would reduce noise levels drastically
(no-one cared about fuel that much these days).
The tests were successful in the sense that it could be done, but apparently the flying skills required, the fact that different approach
procerures should be used depending on the weather conditions (you do get a steeper descent rate whick is not desirable in low visibility
conditions) and the wind-up time for the engines to go from idle or very low power settings to TOGA (making go around a potentially risky
affair, especially because of the steeper descent) caused the idea to be abandoned. So this is a very old idea indeed. Maybe new
technology has taken away some of the downsides, but definitely not all I would imagine.
And if this is used as standard procedure today (UPS?), how would that work? Only with visual approach I gather, because there's no way
you can stay on the ILS glidepath with your engines idled. The Turkish airlines crash near EHAM proved that more than sufficiently! And
would ATC allow you to deviate from the normal approach procedure? Again, I think not (at least not on busy airports).
![[-]](http://www.fspassengers.com/forum/images/collapse.png)