Another incident ?
07-25-2024, 12:32 PM
#201
Strike averted!
Joined APC: Mar 2015
Position: B737
Posts: 3,781
A full scale deflection requires a go-around. I do not advocate ducking under on a minimums IFR approach and I think that’s where some assumptions on adjusting aimpoint are being made. I’m assuming visual conditions and maintaining a glide path within legal limits (you can still adjust an aim point with PAPIs still showing white). Why would you need to go full scale? Thats not accurate.
07-25-2024, 01:10 PM
#202
Strike averted!
Joined APC: Mar 2015
Position: B737
Posts: 3,781
Im reading this conversation and wondering what happened to your landing data. Is it not predicated on flying the glide slope to the runway with a normal flare? If you have good data to stop on the runway available, why do you need to duck under(adjust aim point, etc.)? Do you have any data for your duck under? In my experience, the box stopping distance numbers are pretty easy to beat.
If you fly per the FOM/AOM/landing data and it turns out braking is NIL and you slide off. You are covered. Trying to force it down early has a long track record fatal accidents.
If you fly per the FOM/AOM/landing data and it turns out braking is NIL and you slide off. You are covered. Trying to force it down early has a long track record fatal accidents.
Landing in MDW, BUR, and SNA under wet conditions and max braking (heavy 800 let’s say) may bring a very low margin (zero is a positive stopping margin per the company).
I post this just as a procedural review in the context of the discussion.
07-25-2024, 05:58 PM
#206
Gets Weekends Off
Joined APC: Feb 2010
Posts: 2,339
(and by the way, you are wrong. The HUD landing logic follows the glideslope until something like 45 feet and then starts a pre-programmed flare that is time/rate-based. Also, there is no need to follow the HUD that low on a CAT I or better approach. By the time you cross the runway, it's a visual maneuver).
07-25-2024, 06:01 PM
#207
Gets Weekends Off
Joined APC: Feb 2010
Posts: 2,339
I was showing the absolute extreme case to indicate that "adjusting your aim point" does nothing. A normal descent and landing is a 3 degree angle and about a 2 second flare. If you start that maneuver at full scale glideslope/PAPI you only save 150 feet. Therefore "adjusting the aim point" while not also hitting full scale deflection saves even less.
07-25-2024, 06:05 PM
#208
Gets Weekends Off
Joined APC: Feb 2010
Posts: 2,339
For those in favor of "adjusting your aim point", please tell me what you are doing. What was your starting aim point? What is your adjusted aim point?
Personally, when I land on a short runway, I put the flight path vector right at the 1,000 foot markers until 30 feet and flare. The glideslope is within 1 dot, the descent rate is less than 1,000 fpm, and I touchdown at 1,200-1,400 feet. That is a completely normal landing for MDW or BUR. the biggest variable is your flare time/speed. Adjust those, not your aim point.
Personally, when I land on a short runway, I put the flight path vector right at the 1,000 foot markers until 30 feet and flare. The glideslope is within 1 dot, the descent rate is less than 1,000 fpm, and I touchdown at 1,200-1,400 feet. That is a completely normal landing for MDW or BUR. the biggest variable is your flare time/speed. Adjust those, not your aim point.
Last edited by 2StgTurbine; 07-25-2024 at 06:40 PM.
07-25-2024, 07:16 PM
#209
Strike averted!
Joined APC: Mar 2015
Position: B737
Posts: 3,781
The AOM 12.1.1 specifies that using HUD data (as in PWB) for an AIII approach reduces stopping margin by 1150’ from calculated stopping margins.
I think that’s what they are getting at…but we rarely do a real A3 approach, and our FO’s don’t use the HUD.
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