cruise speed bugs

md-100 · 2nd Jan 2007, 18:10

WHat bug setting do you use when flying at cruising altitude??? (of course old-fashion aircraft, because I guess pilots who fly LCD just watch discovery or whatever while flying at cruising altitue

)

I fly MD80 and set my 4 bugs as follows: VMO, VminManuv, e/o speed, and e/o level off altitude

what about you??

Old Smokey · 3rd Jan 2007, 02:39

That sounds like a pretty good choice of settings md-100, and a fairly good emulation of what is on display or available from the FMC in more modern aircraft. I can't quite figure out why you'd want to set VMO, even the MD-80's grand-mother, the DC9, had a VMO/MMO "barber pole".

Minimum manoeuvering speed is a good idea, that is on full time display in the modern EFIS display, but don't forget to add about 10 knots above 25,000 feet, and 20 knots above 30,000 feet to account for EAS Vs CAS variation from your low-level manoeuvering speed (Compressibility effects and a few other Reynoldsy type things).

Regards,

Old Smokey

Tee Emm · 4th Jan 2007, 10:34

You could also set a moveable ASI bug at Vref40flap+ 100 knots (B737). Example if VRef 40 is 130 knots then 230 knots is a safe speed while you sort things out. Useful as a ball-park figure if you happen to stall at high altitude and you aim to descend as part of the recovery to safe level flight where you will minimise chances of getting into a secondary stall if you attempt a too early level out after recovery. Also a handy figure to remember in a high altitude hold above 25,000 ft.

blue_side_up · 6th Jan 2007, 12:44

On the Classic, our SOP's have us set the ASI bugs at Vref (double bug), and Vref+110 (double bug). Vref+110 is our minimum clean cruise speed, and is conveniently very close to our 3-eng drift-down speed. We reset the bugs for landing (Vref double bug, 1 bug Vref+40, 1 bug Vref+80 all related to flap speeds) at top of descent.
Altimeter bug is set to 3-eng drift down alt, and minimum for the approach at TOD.

md-100 · 6th Jan 2007, 18:12

Quote:

I can't quite figure out why you'd want to set VMO, even the MD-80's grand-mother, the DC9, had a VMO/MMO "barber pole".

Ok, it's a lower speed wich consider a 45 bank angle, so it is the max crusing speed you can bank 45 degrees safely.

Old Smokey · 6th Jan 2007, 19:30

md-100, Again you've quite nicely managed to emulate what the "more modern" EFIS displays

Keep up the good work

Regards,
Old Smokey

md-100 · 6th Jan 2007, 20:06

Oldsmokey, I am the first "human EFIS". I rent myself for non EFIS aircraft as a modern EFIS

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