DA, DH at decision point....
03-05-2008 | 05:43 PM
#11
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From: B737/FO
I had this discussion with our chief pilot today. To be honest, I had never really thought about it this way. He posed the question, for checkride and training purposes, is it a bust or inappropriate to descend below DA at the point a missed approach is executed. Now we are just talking about 10 or 20 feet as the missed approach is executed, because a descent is imminent transitioning from your flight profile. Any thoughts would be great.
Decision Altitude (DA) should be interpreted similar to Decision Speed (V1). DA is point at which decision is made to execute missed approach, and assumes some altitude loss as aircraft transitions from a stabilized approach to a missed approach or go-around configuration. MDA is a "minimum altitude"--no tolerance for going below.
03-06-2008 | 05:56 AM
#12
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I had this discussion with our chief pilot today. To be honest, I had never really thought about it this way. He posed the question, for checkride and training purposes, is it a bust or inappropriate to descend below DA at the point a missed approach is executed. Now we are just talking about 10 or 20 feet as the missed approach is executed, because a descent is imminent transitioning from your flight profile. Any thoughts would be great.
Depends a lot on the machine and the approach. Doing a CatII/III you don't pull the gear UNTIL you have positive rate and are moving away from the rocks. It is possible on a go-around at DH on a Cat III to touch down while going around. So, what is the answer by Mr. Chief Pilot?
03-06-2008 | 06:02 AM
#13
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Another question comes to mind. Lets say you start to
"execute" the missed approach and you drop 20-30 feet below the DH. At that point you see the approach lights or thresh hold or whatever. Do you continue the missed or cut the power and come in for a smoooooth landing?
"execute" the missed approach and you drop 20-30 feet below the DH. At that point you see the approach lights or thresh hold or whatever. Do you continue the missed or cut the power and come in for a smoooooth landing?
The proposal is not very realistic. In a Cessna 182, you are not going to go below DH 20-30ft due to inertia so going that low could be construed as 'busting mins'. In a jet, you would have to pitch the nose BACK DOWN contrary to the thrust line from go-around thrust, re-trim and cut power all of which would violate the 'stable approach' criteria.
Unless you are on fire and running out of fuel and the missed approach takes you into a Level 5 thunderstorm, don't try your cut power approach...
03-06-2008 | 08:46 AM
#14
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From: ATP, CFII, MEI, Chief Flight Instructor, Charter Captain CE402, CE421, BE58
Well, mr. chief pilot said, referring to Cat II approaches in a heavy airplane, that the airplane will likely touch the mains on the go. I don't believe that goes for Cat III approaches, but I'm not sure.
Thanks for everybodys input.
Thanks for everybodys input.
03-06-2008 | 08:49 AM
#15
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From: Engines Turn or People Swim
If it applies to CAT II, how could it NOT apply to CAT III?
03-06-2008 | 11:41 AM
#17
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From: E145 Gear Swinger
Just to be an echo of what everyone else has said...MDA is a hard altitude. For an instrument ride or IPC it's +100/-0 feet on an MDA. As for the DH/DA, that's when you make the decision to go around. If you're making this decision at the DA, then you most likely still in the soup. Since you can't see, you want to make the maneuver somewhat expeditious, yet smooth at the same time. I agree, if you lose more than 20 feet past the DA in a single-engine cessna, then you've done something wrong. If you're in a 747, that's a different story...It's all relative.
03-06-2008 | 11:53 AM
#18
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From: B737/FO
This might help confirm as well. From the missed approach section of the FAA ATP Practical Test Standards:
"Going below the MDA or DA/DH, as appropriate, prior to the
initiation of the missed approach, is considered unsatisfactory
performance. However, satisfactory performance may be concluded
if the missed approach is properly initiated at DA/DH and the
airplane descends below DA/DH only because of the momentum of
the airplane transitioning from a stabilized approach to a missed
approach."
In short, you can't descend below unless missed approach has been initiated (or runway is in sight of course).
"Going below the MDA or DA/DH, as appropriate, prior to the
initiation of the missed approach, is considered unsatisfactory
performance. However, satisfactory performance may be concluded
if the missed approach is properly initiated at DA/DH and the
airplane descends below DA/DH only because of the momentum of
the airplane transitioning from a stabilized approach to a missed
approach."
In short, you can't descend below unless missed approach has been initiated (or runway is in sight of course).
03-06-2008 | 12:09 PM
#19
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From: My seat smells like cat pee
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