Gear Down

Guest · Tue Mar 13, 2001 8:47 pm

Hi folks!

Here are some questions for the pilots out there... When do you select gear down? Does this depend on the distance to the airport- eg not selecting gear down to reduce drag and fuel flow as long as possible? Speed? To slow aircraft down to be right on the glideslope? How do you anticipate speedwise before you select down? How much in knts do you actually loose when the gear is down? (eg with a 737) What about jets vs props?

Thanks,

SabenaA340

A319Pilot · Tue Mar 13, 2001 11:32 pm

Each airplane has an appropriate speed and time to have its gear down. Usually you lower the gear in the downwind leg, as you go reducing the speed down to Vref for the landing flap config. In a straight-in ILS approach, you usually lower the gear not after passing the outer marker. Reducing the plane's speed using gear and flaps is in fact an art. The ideal approach is made with idle thrust, from the top of descent down to the final approach fix, where the plane should be full configured for landing, at its VREF and with the engines developing power. The "art" is to start the speed reduction in a mannet that the speed is slowly decreasing as you add flaps and gear. If you lower the gear too early, you'll have to add power to compensate for the increased drag, increasing fuel consumption.
In the Airbus, we usually start the speed reduction from 250 Kt at around 7 miles from the Outer Marker, or 12 miles from the runway. We first select flaps 1 at a speed below 230 Knots. Then when the speeed decays below 200 we select flaps 2. Then gear down, flaps 3 below 185 and flaps full below 177. The plane should be fully configured for landing at the final approach fix, or at final and no lower than 500 ft in a VFR approach.

Guest · Wed Mar 14, 2001 3:26 am

There really is no set rule about lowering the gear, however it is best to have it down before you go over the fence! I remember going into LAS once, and they ket me really high for a long time, so as soon as I was cleared to decend I dropped my gear and put some flaps in, however on the way bakc to SNA, made straight in for 19R which made my final about 20 miles! So I did not put it down until about 5 miles away as I really did not need to to create drag on that approach, but more to be able to taxi after I landed! Smile

Iain

A319Pilot · Wed Mar 14, 2001 3:52 am

That's it Lain! Good judgement will always be the rule! The landing gear may be the only way to increase the drag once the flaps are lowered in some models of airplanes. Good planning and thinking in advance are the rule to operate in congested airspace, where the ATC can let you get high and fast on approach.

They say that some time ago an ATC controller asked the pilot of a jetliner to reduce its speed to 200 Knots and descend at 2500 ft/min. The captain said "Sorry, I can't descend with this speed and rate of descent" The controller said "Hey!! Use your speedbrakes!! " and the captain said "The speedbrakes are made to correct MY poor planning, not yours" Smile/happy/getting dizzy

Guest · Wed Mar 14, 2001 4:41 am

>>The controller said "Hey!! Use your speedbrakes!! " and the captain said "The speedbrakes are made to correct MY poor planning, not yours" <<
LOL Smile

Iain

c172akula · Wed Mar 14, 2001 8:22 am

Sabena, all these replies seem to come from the "big boys", I'll give you a perspective from a small Piper Twin Commanche setting up for an ILS approach. Generally after being vectored in to intercept the localizer, we'll wait to see the glidescope indicator come down, when it is just above centered we perform a BUMPS check,
brakes
undercarriage
mixture
props
switches

by dropping the gear at that point there is enough drag that the little plane will begin to descend perfectly on the glidescope, with minor power adjustments. Big thumbs up

Guest · Wed Mar 14, 2001 9:14 am

C-172 mine was not on an airliner, but a 172 RG, so that is probably the smallest plane with retracts! I have nevre heard of BUMPS, we always used GUMPBLES:
Gas
Under carrage
Mixture
Prop (although I normally left that till final or it got to loud)
Breaks
Lights
Engine Instruments
Seat belt
Also I guess you are new here so just want to welcome ya!

Iain

Bryan Becker · Wed Mar 14, 2001 11:20 am

Well yes there are airports who have you put your gear down at a certian time. like Tokyo's New Airport and some other airports you have to have your gear down before you reach the coast to prevent ice blocks from falling and ECT.....................! Smile

c172akula · Wed Mar 14, 2001 11:28 am

Guess you got me beat, the 172 wins. As for the acronyms I'm sure flight instructors got a whole bunch of different ones, BUMPS is just one of thousands I'm sure. If your into the IFR stuff you know how many more come into play. And thanks for the welcome!
Laugh out loud

Guest · Wed Mar 14, 2001 11:32 am

Q. How does a fighter pilot know when he's landed gear up?
A. It takes full power to taxi to the ramp. Big grin

Mr Spaceman · Sun Mar 18, 2001 5:36 am

Hi guys. What about some actual numbers with reguard to SabenaA340's question on how much airspeed you loss when you extend the gear. For example, when flying the Twin Commanche, C-172RG or the "big boys" aircraft, and your cleaned right up, how much airspeed will you loss if you dump ONLY the landing gear? I myself have always wondered about this.

Guest · Sun Mar 18, 2001 6:43 am

Spaceman it depends on so many things. You guys are always after fixed numbers whoever in this industry there are very few!
Iain

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