Jet final APCH ROD
Only half a speed-brake
Thread Starter
Jet final APCH ROD
Hello there,
is it correct to assume that (737 classic):
In landing configuration at 30° flap setting, the slower she flies (closer to Vref+5) the higher ROD?
In other words, when hot'n'high, one configures for landing ASAP and then (e.g. Vref 125, Vapp 130) at 145 kt, the aircraft is positively aiming half-mile infront of threshold. Slowing down to Vapp involves pitch change that shifts the PAPIs down the FWD window. Is this not just an optical reference, will not slowing down yield a higher ROD?
Or perhaps the best wording to the question: In the example given is the a/c on the "left" side of drag/thrust curve and will slower speed thus provide for steeper approach angle, or not?
Thanks,
FD.
Post scriptum: Strictly VMC, 45%N1 and 141kt at 500', but you really did not want to ask, did you?
is it correct to assume that (737 classic):
In landing configuration at 30° flap setting, the slower she flies (closer to Vref+5) the higher ROD?
In other words, when hot'n'high, one configures for landing ASAP and then (e.g. Vref 125, Vapp 130) at 145 kt, the aircraft is positively aiming half-mile infront of threshold. Slowing down to Vapp involves pitch change that shifts the PAPIs down the FWD window. Is this not just an optical reference, will not slowing down yield a higher ROD?
Or perhaps the best wording to the question: In the example given is the a/c on the "left" side of drag/thrust curve and will slower speed thus provide for steeper approach angle, or not?
Thanks,
FD.
Post scriptum: Strictly VMC, 45%N1 and 141kt at 500', but you really did not want to ask, did you?
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Bit confused by all the 'PAPI motion', FD, and I think worrying about 'drag curves' just complicates the issue?, but in essence the slower the g/speed the less the required ROD for a GIVEN approach angle. The problem comes if you slow TOO LATE, and then, yes, the a/c will go higher on the approach, making the problem worse, whereas if you could slow earlier you have more time to lose the excess height, and of course, if you could slow to ZERO g/s (ie a Harrier) you would have forever to lose the height (until the fuel runs out or you get bored
)
The classic example is when descending near terrain where you wish to limit ROD to, say 3000fpm for GPWS protection, but you are high. 3000fpm at 300 kts will keep you high, but 3000fpm at 210 kts will give you more time to lose the height.
Is that what you asked?
)The classic example is when descending near terrain where you wish to limit ROD to, say 3000fpm for GPWS protection, but you are high. 3000fpm at 300 kts will keep you high, but 3000fpm at 210 kts will give you more time to lose the height.
Is that what you asked?
I'm not qualified (on type) to answer your question, but in the interests of clarification I would ask this.
Are you asking about recovering a high approach by slowing down? Because, of course, you can keep the same RoD (ft/min) and by reducing speed that becomes a higher RoD in ft per mile . And thereby regain, say, a non-precision app profile.
But if the question's about B737 performance, I'll just leave it to others.
Are you asking about recovering a high approach by slowing down? Because, of course, you can keep the same RoD (ft/min) and by reducing speed that becomes a higher RoD in ft per mile . And thereby regain, say, a non-precision app profile.
But if the question's about B737 performance, I'll just leave it to others.
