Ultra steep climb after take off

[tonymerry 0]

Most of my flights are short & so fuel is in the 10, 000 lb range. The usual initial altitude from ATC is 5,000 ft. With this light aircraft I use climb 2, but initiating the autopilot at about 1,000 ft results in a climb of 4 to 5 thousand fpm & a speed drop to stalling point. Is this realistic, or do I have to fly manually to 5,000 ft, or is there a way to limit the climb prior to take off?  I have tried setting a climb of say 1,500 fpm in the vertical speed window, but pressing autopilot switches this off.

Tonymerry

[scandinavian13 5,192]

Most of my flights are short & so fuel is in the 10, 000 lb range. The usual initial altitude from ATC is 5,000 ft. With this light aircraft I use climb 2, but initiating the autopilot at about 1,000 ft results in a climb of 4 to 5 thousand fpm & a speed drop to stalling point. Is this realistic, or do I have to fly manually to 5,000 ft, or is there a way to limit the climb prior to take off?  I have tried setting a climb of say 1,500 fpm in the vertical speed window, but pressing autopilot switches this off.

Tonymerry

 

Hey Tony - what you're likely seeing is the autopilot (in VNAV mode), trying to race to the commanded speed, which is usually pretty low. As an example, if your V2 is 150 (just an example), your initial climb speed should be about 160. If your speed is higher than this, the autopilot will use pitch to modulate speed. In other words, it will pitch the nose up to drop the excess airspeed.

 

Proper technique would be to follow the flight director from rotation on. This will (help to) ensure that you fly the departure profile correctly, along with ensure that you pass the controls over to the autopilot while you're "seeing the same picture."

 

I'm guessing you haven't flown the tutorials, or didn't pay much attention to the departure. I'm willing to bet that you'd learn a bunch by re-flying at least that much of the tutorial. Additionally, the FCTM has a very good and graphical depiction of the proper climbout.

 

The basics are:

Set power.

Pitch for speed.

Climb at V2+10 until accel altitude (which you set on TAKEOFF REF page 2)

Pitch over slightly, accel and retract flaps up to 250.

Reaching 250, modulate pitch to maintain 250 until, 10,000.

[Guest]

Hi Tony.

 

Are you familiar with Noise Abatement Procedures? (NADP) If you follow this procedure you'll be taking off identically to my operator.

 

There are two departure procedures defined, NADP 1 or NADP 2. Most departures follow NADP 2 guidelines, following this guidance will stop you climbing up at barbaric rates to the stop Altitude/Flight Level!

 

As I mentioned every operator will handle this differently and might differ from other advice you might be given.

 

• Before you depart Arm the A/T and engage a roll mode (HDG or LNAV)
• Engage TOGA, rotate and climb to 1000ft at a minimum of V2+15kts
• At 1000ft AGL Engage A/P or fly manually and Bug Up (set airspeed bug to up)
• Retract the flaps on schedule
• Once the Flaps are up select a CLB Mode (V/S, LVL CHG/VNAV)

Now as you mentioned the 737-800 flying light will climb at quite a rapid manner, some departures at certain airports may require you to level off at an altitude as low as 3000ft. In this case the stop altitude would have been set in the MCP window for departure and the AFDS FMA will annunciate ALT ACQ if the F/D is engaged. If this happens during the departure sequence BUG UP if not done so already and continue to retract the flaps.

 

My operator instructs us to reduce the rate of ascent/descent below FL200 within busy TMA's/high density traffic areas to 2000fpm at 2000ft to level-off and 1000fpm at 1000ft to level-off (unless a restriction set by ATC or procedure exists) The best mode to do this is obviously V/S and is frequently used on departures, primarily to prevent unnecessary TCAS warnings.

 

Remember to treat the Autopilot/MCP as a toolbox, you use whatever mode you need to get the job done. Contrary to popular belief we don't LNAV/VNAV everywhere!

 

I hope this hasn't been useful and as easy to understand, any further questions please don't hesitate to ask.

 

Sam Breese.

[tonymerry 0]

Thanks guys I'll try the various suggestions. I was subscribing to the belief that LNAV/VNAV was used more than it is. Regards  Tony

[Guest]

I hope this hasn't been useful and as easy to understand, any further questions please don't hesitate to ask.

 

 

I have absolutely no idea why I wrote "hasn't". HAS.

 

Sam Breese.

[Driver170 42]

 

 

My operator instructs us to reduce the rate of ascent/descent below FL200 within busy TMA's/high density traffic areas to 2000fpm at 2000ft to level-off and 1000fpm at 1000ft to level-off (unless a restriction set by ATC or procedure exists) The best mode to do this is obviously V/S and is frequently used on departures, primarily to prevent unnecessary TCAS warnings.

 

 

Thats in my policy

 

Climb and Cruise Procedure - Pilot Flying and Pilot

Monitoring < RYR >

 

Flight crews will reduce rate of climb to a 2000 FPM at 2000 feet to

level-off and 1000 FPM at 1000 feet to level-off. This restriction will

be observed below FL200 when operating in busy TMA’s or high

density traffic areas.

[Spin737 102]

Most of my flights are short & so fuel is in the 10, 000 lb range. The usual initial altitude from ATC is 5,000 ft. With this light aircraft I use climb 2, but initiating the autopilot at about 1,000 ft results in a climb of 4 to 5 thousand fpm & a speed drop to stalling point. Is this realistic, or do I have to fly manually to 5,000 ft, or is there a way to limit the climb prior to take off?  I have tried setting a climb of say 1,500 fpm in the vertical speed window, but pressing autopilot switches this off.

Tonymerry

 

You shouldn't be getting close to a stall. Something is amiss if you are getting that slow.

 

Pressing the autopilot button shouldn't turn off the V/S mode.