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I can't believe what I am reading!

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I can't believe what I am reading!

Old 18th Aug 2000, 07:07
  #21 (permalink)  
quid
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I think that what you want, altitude or airspeed may depend on what aircraft you are flying. I have no experience on light twins, but more time than I care to think about on *big iron*.

Seeing as how a forced landing in a field is not an option on heavies, once I've cleared the obstacles, give me SPEED every time. If I've lost one engine, I may soon lose another. In that case my minimum control speed is 210 kts. If I'm at Vx to get away from the ground, I'm well below that. Also, there may be some damage that the *book* doesn't cover. As previously mentioned, if the American DC-10 (not Eastern) had kept the speed, they would probably still be here.

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[This message has been edited by quid (edited 18 August 2000).]
 
Old 18th Aug 2000, 09:38
  #22 (permalink)  
Tor
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Quid - In a light twin you don't want to be at Vx either (since you woudn't care about the angle). You would be at Vy as you would like to get away as fast as possible. When you have reached safe altitude you would accelerate to what ever might be convinient eg. cruise climb.

Having flown a DC-10 simulator, I was taught that you would like to be at V2 - V2+15 if you lose an engine (around 175 kts if I remember correctly a MTOM) untill clear of obstacles and then accelerate to BROC-speed or 250.

If you lose an engine on the ground roll after V1 wouldn't you climb at V2. If you accelerate to 210 kts you can't be sure you clear the obstacles - no?

Tor

[This message has been edited by Tor (edited 18 August 2000).]
 
Old 18th Aug 2000, 10:24
  #23 (permalink)  
quid
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Wink

Tor-

If I lose one at V1, I'd certainly climb at V2 to 1000' AGL, then transition (flaps zero) and climb to 1500' AGL. Our obstacle clearance data assumes I will do that. If VMC (or at a familiar location) where obstacles are not a factor, I'd tend to be on the fast side of V2, just in case. <g>

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Old 18th Aug 2000, 17:17
  #24 (permalink)  
Tor
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Quid - so you do admit you prefer height over speed (or atleast your SOP does)

Tor

[This message has been edited by Tor (edited 18 August 2000).]
 
Old 18th Aug 2000, 21:08
  #25 (permalink)  
quid
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Smile

Tor-

Altitude over speed? No, I didn't say that.

First, there can only be one SOP (and I help write them at my carrier, so I've got to follow them). <g> The SOP has to cover the worst case scenario to clear obstacles in the t/o flight path. We choose to fly at V2 to 1000' prior to transition to clear obstacles. We could have chosen to transition at 400', the FAA minimum.

Now, if I didn't have to follow an SOP, when I lost one, ONCE I'M CLEAR OF OBSTACLES, I'd accelerate and get it clean ASAP.

BTW, V2 is significantly slower than Vx in the t/o configuration.




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Old 19th Aug 2000, 01:15
  #26 (permalink)  
Tor
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quid -

The thread that the original post refers to was about what to do imediately after T/O (ei. before obstacles has been cleared).

I agree once you have cleared obstacles there is no point in flying slow. I'am only flying light twins so slow is of course relative . My only experience with Big Irons is from a JAA MCC course (European for CRM. It included 21hrs on a DC-10-30 sim - great fun )


Tor
 
Old 19th Aug 2000, 02:10
  #27 (permalink)  
Tinstaafl
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Differences in operating & performance techniques are significant I think.

Jet types aren't necessarily anywhere near Vx or Vy when they're at V2. They can be some way behind the drag curve. In this case a speed increase can improve performance.

Light A/c though are usually at or near max performance speeds very shortly after take-off.
 
Old 24th Aug 2000, 01:26
  #28 (permalink)  
Waloo
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Sorry if I'm late.

KIFIS, are you refering about this threat !?
http://www.pprune.org/ubb/NonCGI/For...ML/001111.html

Anyway, funny to see that the guy who gave me the check on type was also a former crop duster...No need for height here, only speed.

Now, speaking about light twin just after T/O . No single crop dusting, no heavy jet with big amount of thrust, no... whatever.
JUST LIGHT TWIN NEAR MAX GROOS WEIGHT AFTER T/O.

If, in case of an engine failure you lose more rapidly speed than height . Well, it's obvious, I will keep my blue line and look for this height.

All I want is seeing the "danger zone" as short as possible.
 
Old 24th Aug 2000, 16:50
  #29 (permalink)  
Ex Bus Driver
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This is in reply to ORAC's message of 13 Aug.

I believe he was referring to the American Airlines DC-10 accident at ORD in 1979 or so.

The pitch bar on the HSI normally commands
V2+10kts. With the loss of an engine, The pitch bar commands V2. The Captain followed
the commands as he was trained to do, and the left wing stalled, since the slats had retracted with the loss of hydraulics resulting in the crash. Subsequent simulator studies proved that if V2+10 had
been maintained, the aircraft would have been flyable!

Unbelievably, the procedure remained that the Flight Directer MUST be on for T/O, with
the expectation, that if a similar event were to occur, one was expected to ignore the pitch bar command and fly "through" the
bar! Talk about being a "slave" to the automatics!

EBD
 
Old 25th Aug 2000, 22:34
  #30 (permalink)  
Victor B1a
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Cool

OH DEAR!
Cx. the quote below chaps.

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[quote]Watch well lest the ground riseth up and smiteth thee.[quote]
 
Old 26th Aug 2000, 00:33
  #31 (permalink)  
Puritan
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Follow the flight-director at your peril - maybe on the ILS it's great but on take-off it (sometimes) can command daft pitch angles - as it does too with a windshear case - thus try and fly those pitches angles and watch your airspeed pointer !

(all imho, of course)
 
Old 29th Aug 2000, 22:57
  #32 (permalink)  
ironbutt57
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flight directors on takeoff have to be "looked through" in many situations..while V2+15 is the optimum climb speed for most swept-wing aircraft while still in the take-off config...if i lost an engine at V1 i would climb at V2...if i had already accelerated to V2+15..then maintain that speed unless collision with an obstacle is iminent...the dc-10 crew proved a an old adage "ifit ain't broke don't fix it" to be true the airplane was climbing, and had no obstacle..but ingrained procedures instead of old-fashioned airmanship prevailed, and the and aircraft control was lost...the crew had no way of knowing the configuration of their wing..in the few short seconds they had to make the decision that we have had years to second guess...i personally would climb at a slightly higher speed than V2 if a violent engine "event" had occurred, and the aircraft was climbing at an acceptable rate...
 
Old 3rd Sep 2000, 01:40
  #33 (permalink)  
ADUBI
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That's the point!

eng fail btwn v1 and v2 -> maintain v2
eng fail btwn v2 and v2+15 -> maintain gained speed
eng fail btwn v2+15 and higher speed -> convert excess speed to hight and maintain v2+15,
because this speed equals about vx (for JET a/c).
That's what improved climb is all about.
Big difference between PROP & JET?
PROP vx is much closer to vs than in JET aircraft.

So acceleration may make sense, i.e. if the lim fac is a far out obstcl. and your in a JET. On the other hand, acceleration (during night in IMC) in a close in obstcl. situation will screw your day.

RGDS
ADUBI
 
Old 4th Sep 2000, 02:33
  #34 (permalink)  
skynet737
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KIFIS--- Height or Speed... wouldnt it really depend on what stage of the flight you are.. in a b737 if i lost both engines at cruise id maintain height till i got down to my best L/D speed ( pretty much the same if i lost one engine only ) before i started to descend.... basically converting EXCESS speed into height.

At toff ud follow your toff segments to meet obstacle clearance climb gradients( a min req of 2.4% on b737 in the second segment.... where ud probably be maintaining toff flaps, toff thrust, gear up, and speed of v2 to v2 + 20). the third segment ud be cleaning up ... and the height would basically depend on the obsatcles in your toff path and being able to clean up and set MCT on your operating engine within the toff thrust time limit of your engine.

so u pretty much got it... u need the speed but only so much ( best L/D ).... after which anymore is only a DRAG.
 

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