B: Re: OT // C90 crash in NC; NTSB Prelim published

[BobsV35B at aol.com]

Good Morning John,
 
After reviewing the preliminary report, I am even more convinced that the  
better plan for that approach and the reported conditions would have been to  
execute the approach with the mind set that it was going to be a circling  
approach. 
 
I probably would have done a classic Dive and Drive, so that I would be in  
position for a straight in if the opportunity presented itself, but my plans 
and  organization would be on setting up for the circle.
 
Either the dive and drive or the electronically generated glide path would  
have been OK as long as the level off was started soon enough such that the  
circling MDA was not violated.
 
I think it would have been foolish to be flying that approach in a King Air  
at 120 knots. The King Airs that I flew tended to like about 105 knots. I am 
not  sure if the newer ones like to be faster, but 120 knots is getting too 
close to  C category for my comfort. Category B allows circling with one mile 
visibility  and that seemed to be a sure bet that day. 
 
The problem might have been the lower cloud deck at three hundred feet.  That 
is even more reason to stay level at the circling MDA and look things over.  
If it didn't look good on the first trip around the field, it would be 
perfectly  acceptable to make another circle as long as adequate visual references to 
the  airport were available and the circling limits (Including the lateral 
area  limitations) were not violated.
 
The circling MDA is only twenty feet higher than the straight in. It  seems 
to me that it well worth giving up that twenty feet to gain the extra time  and 
safety at the MDA while circling to find a safe approach path to the  runway.
 
It is my idea of a classic situation where the circling approach should  have 
been the plan and the straight in only considered if conditions were much  
better than expected.
 
The safety of flying level at the MDA while one thinks things over is  
something that most pilots do not fully appreciate.
 
I need time to think! Don't most people find that extra time useful?
 
Happy  Skies,

Old Bob
AKA
Bob Siegfried
Ancient Aviator
628 West  86th Street
Downers Grove, IL 60516
630 985-8502 
Stearman  N3977A
Brookeridge Air Park LL22


In a message dated 2/17/2008 9:54:05 A.M. Central Standard Time,  
johncollins at carolina.rr.com writes:

Old  Bob,

The GPS RWY approach at Mount Airy is interesting  
http://204.108.4.16/d-tpp/0802/06492G36.PDF

The rate of descent  from JODRI to the threshold is just over 390 ft/NM. 
According to the  preliminary NTSB report, the weather was 2 1/2 miles, rain, 
broken at 300,  overcast at 600.  On the approach, the last radar return on 
final  showed the aircraft at 2000 ft, 1 NM from the MAP. Assuming he crossed 
the  FAF JODRI at 3200, it would mean that he averaged 300 ft/NM to the 1 NM  
point, so it is unlikely he got to minimums and stabilized prior to the  MAP 
and would not likely have been in a position to land, even he was able  to 
see the runway, without circling.

If he had a WAAS GPS and  followed the vertical guidance, the GS would have 
gotten him to the MDA  about 1.2 NM from the threshold, but he would have had 
little time to spot  the runway and make a straight in landing.  If he was 
flying the  approach at 120 Kts, he would have had to maintain just over 780 
ft/min  descent rate.
I think a dive and drive at 1000 ft per minute would have  worked better, 
with a level off starting 100 ft before the MDA, that might  have given him 
about 2 NM to find the runway.  I personally don't  like descending that 
fast, but for this type of approach, one must be  aware of the higher than 
normal descent angle to the runway and either  slow down or descend more 
rapidly if they expect to be able to land  straight in.

One other point, if this approach was flown with a WAAS  GPS coupled to the 
autopilot for vertical, the vertical GS would not  appear until just past 
EFOLE, only 1 NM from the FAF, or only about 30  seconds at 120 Kts.  This 
might not provide sufficient time for  setting up the autopilot in order to 
capture the GS.  If I were  planning on using the WAAS advisory GS, I would 
activate vectors to final  at EDLIF and intercept the GS at 4000 ft.

Any  comments?

Regards,

John D.  Collins






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