Reduced power takeoffs reduce wear on the engine by reducing the exhaust gas temperature. More fuel is burned durng a reduced power takeoff since the engine remains at TO power longer than at full power, but is less stressful on the engine. Reduced power takeoffs also allow normal acceleration rate, and normal climbout body angle when the plane is lightly loaded. The Captain is the final authority as to the use of reduced power. Reduced power should not be used if any one the following conditions are present.
1) If the runway is contaminated with snow, slush or standing water
2) If you are taking off with a tailwind
3) Wing anti ice is used
4) Visibility is less than 1 mi
5) If there is a crosswind greater than 10 kts
6) The first flight of the day
7) If reduced TO power is less than climb power use climb power as the min TO power setting
Showing posts with label Aircraft Operations. Show all posts
Showing posts with label Aircraft Operations. Show all posts
Thursday, August 20, 2009
Sunday, August 16, 2009
Aircraft Operations: Takeoff Procedures
Why is it that the approach and landing get's all the attention when it comes to making Youtube video's. The approach and landing is the money shot of aviation clips. What glory is bestowed upon one who can execute an ILS approach. Most people unless they have flown large aircraft believe that you just push the power up, pull the nose up and begin to climb away from the earth making big trees into little trees. Just pull back and look out the window at the passing scenery. Well I have news for you mi amigo. The takeoff is just as prodcedural and intense as an approach and landing. I am using the PMDG 747 here, but this information is largely generic and applies to any large aircraft.
We're going to start our discussion of takeoff procedures from the point where tower calls and tells you to take the active runway and hold. The FMC has all it's data entered. Checklists have been completed.
Upon being cleared into position on the active runway you want to turn on your landing lights and visually confirm the runway is clear and no one is approaching the runway from either end. Yes... people land the wrong way. A simple "clear left", "clear right" will suffice. Roll into position on the centerline and the first thing to check is that my heading indicator and compass are corresponding with the runway heading. My heading bug should be set to the initial course given in my clearance. Usually it's "fly runway heading" so the bug should be set accordingly. I hold my brakes and wait for tower to clear me for takeoff. I scan over the mode control panel one last time and check my engine instruments, flap handle position and TO stab setting. I also take a quick look at my pedestal and overhead panel. Everything looks good.
After receiving takeoff clearance I stand up the throttles to the 12 o'clock position and wait for 4 spooled and stable engines. If an engine parameter looks off I will abort the takeoff. If everything is OK I either engage the autothrottle which automatically advances the thrust levers and sets TO power according to the FMC's calculations or I advance the throttles to TO power manually. The NFP will confirm TO power is set.
With foward pressure on the yoke to assure we have nosewheel steering as we accelerate down the runway the first thing I am looking for is that my airspeed indicator comes alive. A failure of either the FO's or captains airspeed indicator is a reason to abort. The first callout from the NFP will be 80 knots. I will check that my airspeed indicator is in agreement. If all is still good I continue with the takeoff roll continually referencing my engine instruments, my centerline, and my airspeed indicator making sure we have no signs of an engine failure as I can abort before we reach V1 which is our takeoff decision speed. V1 is the airspeed at which we are going flying unless the captain has serious doubts the plane will become airborne and remain airborne. V1 is the speed at which you can stop on the runway remaining using maimum wheel braking, spoilers to stop the airplane. Reverse thrust can and should be used, but it is not a factor in calculating the decision speed.
Upon reaching V1 hands are removed from the throttles. The abort option has ended. Whatever happens now you are talking it up with you and will deal with it there. If we lose an engine after v1 there will be no action taken until 1000' AGL except to silence a bell. By not touching anything until 1000' we remove the chance of shutting down the wrong engine. The failing engine may still be producing reduced power. Any power is good power! We will take any power this engine can produce during this extremely critical phase of flight even if it means further damage to the engine. We need to get to 1000' AGL.
The NFP calls out VR this is the point in the takeoff roll we rotate the aircraft to the climb attitude and begin to climb away from the runway. The next visual cue we are looking for is a positive rateof climb on our VSI. With the VSI showing a rate of climb we retract the landing gear. Next we focus our attention to the airspeed and attitude indicator. We are looking for the correct nose up angle for the corresponding climb speed which is set in the MCP and shows up as a bug on our air speed indicator. The V2 plus 10 kts speed set here is 180 knots and we pitch for it. V2 is the speed we want to fly if we lose an engine on takeoff. We fly V2 +10 if all engines are operating. This gives us a buffer of 10 knots in case we do lose an engine. We will have time to identify and correct for the engine failure so as not to drop our airspeed below V2.
We climb out at approximately 10 degrees nose up and 180 knots until we reach 1000' which is our acceleration height. Lighter weights and our climb angle will be greater. It is at this point we want to lower the nose and begin accelerating towards our minimum manouvering speed in clean configuration (flaps up) the minimum manouvering speeds for each flaps setting are shown on the 747's airspeed tape. As you accelerate past these airspeeds we retract the flaps incrimentally until we are clean. Below 10,000 feet we want to maintain our airspeed below 250kts per FAA regs. In the 747 sometimes we are so heavy we need to break this speed limit since our minimum manouvering speed clean is higher than 250kts. When the flaps are up we can set climb power and complete the after takeoff flow and climb checklist. landing lights remain on below 10,000'. Altimeter setting changes to 29.92 after passing 18,000' as we are now in clas A airspace.
And you thought takeoff was something anybody could accomplish. You've see it on Youtube a million times. But you have yet to see it done right!
Here's a clip of a full power takeoff. Visibility was 1mi so a reduced power T/O wasn't an option. Watch it in full screen to see the instruments.
We're going to start our discussion of takeoff procedures from the point where tower calls and tells you to take the active runway and hold. The FMC has all it's data entered. Checklists have been completed.
Upon being cleared into position on the active runway you want to turn on your landing lights and visually confirm the runway is clear and no one is approaching the runway from either end. Yes... people land the wrong way. A simple "clear left", "clear right" will suffice. Roll into position on the centerline and the first thing to check is that my heading indicator and compass are corresponding with the runway heading. My heading bug should be set to the initial course given in my clearance. Usually it's "fly runway heading" so the bug should be set accordingly. I hold my brakes and wait for tower to clear me for takeoff. I scan over the mode control panel one last time and check my engine instruments, flap handle position and TO stab setting. I also take a quick look at my pedestal and overhead panel. Everything looks good.
After receiving takeoff clearance I stand up the throttles to the 12 o'clock position and wait for 4 spooled and stable engines. If an engine parameter looks off I will abort the takeoff. If everything is OK I either engage the autothrottle which automatically advances the thrust levers and sets TO power according to the FMC's calculations or I advance the throttles to TO power manually. The NFP will confirm TO power is set.
With foward pressure on the yoke to assure we have nosewheel steering as we accelerate down the runway the first thing I am looking for is that my airspeed indicator comes alive. A failure of either the FO's or captains airspeed indicator is a reason to abort. The first callout from the NFP will be 80 knots. I will check that my airspeed indicator is in agreement. If all is still good I continue with the takeoff roll continually referencing my engine instruments, my centerline, and my airspeed indicator making sure we have no signs of an engine failure as I can abort before we reach V1 which is our takeoff decision speed. V1 is the airspeed at which we are going flying unless the captain has serious doubts the plane will become airborne and remain airborne. V1 is the speed at which you can stop on the runway remaining using maimum wheel braking, spoilers to stop the airplane. Reverse thrust can and should be used, but it is not a factor in calculating the decision speed.
Upon reaching V1 hands are removed from the throttles. The abort option has ended. Whatever happens now you are talking it up with you and will deal with it there. If we lose an engine after v1 there will be no action taken until 1000' AGL except to silence a bell. By not touching anything until 1000' we remove the chance of shutting down the wrong engine. The failing engine may still be producing reduced power. Any power is good power! We will take any power this engine can produce during this extremely critical phase of flight even if it means further damage to the engine. We need to get to 1000' AGL.
The NFP calls out VR this is the point in the takeoff roll we rotate the aircraft to the climb attitude and begin to climb away from the runway. The next visual cue we are looking for is a positive rateof climb on our VSI. With the VSI showing a rate of climb we retract the landing gear. Next we focus our attention to the airspeed and attitude indicator. We are looking for the correct nose up angle for the corresponding climb speed which is set in the MCP and shows up as a bug on our air speed indicator. The V2 plus 10 kts speed set here is 180 knots and we pitch for it. V2 is the speed we want to fly if we lose an engine on takeoff. We fly V2 +10 if all engines are operating. This gives us a buffer of 10 knots in case we do lose an engine. We will have time to identify and correct for the engine failure so as not to drop our airspeed below V2.
We climb out at approximately 10 degrees nose up and 180 knots until we reach 1000' which is our acceleration height. Lighter weights and our climb angle will be greater. It is at this point we want to lower the nose and begin accelerating towards our minimum manouvering speed in clean configuration (flaps up) the minimum manouvering speeds for each flaps setting are shown on the 747's airspeed tape. As you accelerate past these airspeeds we retract the flaps incrimentally until we are clean. Below 10,000 feet we want to maintain our airspeed below 250kts per FAA regs. In the 747 sometimes we are so heavy we need to break this speed limit since our minimum manouvering speed clean is higher than 250kts. When the flaps are up we can set climb power and complete the after takeoff flow and climb checklist. landing lights remain on below 10,000'. Altimeter setting changes to 29.92 after passing 18,000' as we are now in clas A airspace.
And you thought takeoff was something anybody could accomplish. You've see it on Youtube a million times. But you have yet to see it done right!
Here's a clip of a full power takeoff. Visibility was 1mi so a reduced power T/O wasn't an option. Watch it in full screen to see the instruments.
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