Speed / Thrust Management <10,000 FT

[bob34 124]

Hi guys:

 

Need a little help from the experienced 747-4 folks.

I have a check ride pending from my VA and while I practice for the ride, I'm having a difficult time with speed management in manual flight.

 

Here's the setup:

 

No Autopilot below 10,000 feet. Autothrottle is allowed.

I have to climb to 5000 on runway heading @250kts and manage a turn while climbing to 10,000.

GTW is ~620,000lbs.

 

I have the FMC properly setup to have the speed restrictions for 250/10000 set.

I'm using TO/2 CLB/2 in the FMC.

 

I can't exceed 4000 fpm climb (my dilemma).

 

Using autothrottle and the flight director, I can keep 250kts (usually), but can't keep it under 4000fpm climb. I'm either exceeding 250kts or 4000fpm climb. Autothrottle doesn't seem to be winding the engines down with changes in attitude, but rather insists I increase my climb rate to maintain speed.

My only option is using manual throttle, but I'm all over the place with speed and climb (it's a lot to manage w/out a FO and the power of the engines with a low GW).

 

Clicking Speed / Thrust doesn't seem to have any effect while AP is off.

 

Can anyone think of a way to manage 250kts / <4000fpm climb using AT but not AP? Again - the engines at this low GW just want to propel me to the moon.

 

Any help/advice would be appreciated.

 

Thanks,

 

Bob

[g_precentralis 191]

Stupid rule, if you ask me. If they want to test you to fly manually, than AT should also be forbidden. I would turn off AT after climb power is set and if reach 4k fpm, I would just ease throttles a little bit. Throttle workload at climb is pretty much non existent, you set climb power and just climb, ease a little bit if examiner requires it.

[G550flyer 1,008]

Best thing to do is to lower your thrust. 2,000 to 2,500 fpm is a good target. Derate the the takeoff thrust. As soon as you get into climb mode, set vert speed to 2,500 and the AT to speed hold. This way the throttles will hold your speed and the climb is more manageable. If using manual throttles, make throttle movements in bits and anticipate thrust changes. If you handfly the whole climb, set a lower power setting and select flight level change. Adjust the power to maintain 2500 fpm while you pitch for speed. Just remember as you level off, start pulling power and ease off the pitch to capture. 500 to 1000fpm is a good target for alt capture.

[ESzczesniak 128]

Why are you unable to exceed 4,000 fpm for the check flight? This is a highish climb rate and would typically be avoided for passenger comfort. However, safety comes first and 4,000 fpm is not unreasonable. I can't speak to the 747 specifically, but some pressurization systems start having trouble keeping up getting above 6,000 fpm or so, but 4,000 fpm still seems relatively tame.

 

I do generally agree that if A/P is off, I would minize A/T use, however on the climb I am more likely to ignore this.

 

Anyway, to the point finally. First, what is you minimum clean speed? For the 747, it will often be greater than 250 kts. If this is the case, you should climb at this speed, not 250 kts, even under 10,000' MSL. Heavy aircraft with minimum clean speeds will be granted exceptions to the 250/10k rule. The higher IAS will lower your climb angle and bring the V/S down.

 

Second, are you appropriately derating (not sure what sources you're getting your derates from). If you can safely derate more aggressively, you'll take some power out of your climb and lower your V/S.

 

As a third option, can you increase your gross weight? This will also lower your V/S in the climb.

 

In terms of realism and safety, I would recommend against lowering thrust from the documented safe and appropriate derated climb thrust.  The goal of takeoff and lower level climbs is to get away from the ground as quickly as reasonably possible so that if something goes wrong, you have altitude to trade for airspeed (and time).  While V/S has it's roles, I believe they are very rare and seldom appropriate during a climb.

 

This sounds like a check flight for UVA. Back in the day I used to fly with them and even was a check pilot for a long while. Hopefully I'll get back to flying with them, but life has gotten busy. If this is indeed the VA, I'd send them an e-mail. At least previously, they were a reasonable group of guys and as long as you flew safely and realistically with a reason, would look past exceptions to some of these numbers.

[G550flyer 1,008]

In real world ops, I use V/S every flight. When I flew heavies, we used it during accel and decel. In the DC10 we used it going from v2 plus 10 to minimum maneuver/250. You would call for climb power and vert speed 500fpm(heavy) or 1000fpm (light) at 1500ft. At min/250, we used a FLC mode called IAS hold. At 10, we used V/S again to accel to 330. On descent prior to 10,000, we used the 12 at 12 technique(set 1200fpm  at 12,000 to allow the jet to reach 250 by 10,000 clean). Even in the Gulfstreams we use vert speed every flight. We use 2000fpm after takeoff for passenger comfort as long as there isn't any climb restrictions.. No need to have the boss spill his cognac climbing at 5000 fpm. Most guys use vert speed in the climb because FLC hunts alot and will get sloppy during temperature inversions and wind changes. It also sucks in mach hold. I only use FLC when empty or when the jet is heavy. It's more gentle in pitch changes when heavy. But, in flight sim, you can climb how ever you want.

 

 I almost forgot that if your climb rate was too high in the DC10, you would out climb the cabin and trigger the over pressurization poppet valves. This would happen above FL290(mach change over) because the cabin press system would enter differential mode to maintain normal cabin diff. So you had to watch it when you were light.

[bob34 124]

Thanks for all the replies.

 

I'm not sure the sequence, but on my last test, I was able to activate the "speed" switch on the AT and at least I was able to keep 250kts with throttle rather that attitude adjustments. This gave me a consistent VS during the climb and initial turn.

Previously, nothing would happen when pressing the SPD or THR buttons. I'm sure it's a sequence issue.

 

On a positive note, this has inspired me to put my head back in the manuals and also helped me realize how my flying skills have diminished due to auto-flight. I think I'll make it a habit to hand fly under 10,000 more often. As much as I want the flight to go smooth, I need to keep my pilot skills sharp. I've been over-using the autopilot to ensure I don't screw up my VA flight.

 

Thanks again for the responses. It's been a great afternoon hand flying the 744 and re-reading the manuals.

[kevinh 409]

I wouldn't recommend using the A/T in speed mode in climb, it could create trouble for you on your check ride if the sim misbehaves or the weather throws you a curve ball.  Can you use a heavier weight?  That would result in a lower rate of climb. Otherwise the advice posted by g_precentralis (always wondered what the "Ц" in the sig stands for) to manually set lower thrust is your next best option.  You could use your practice flights to find an EPR or N1 value that will keep you comfortably below 4,000 ft/min.   That would remove your worries and you could concentrate on the flying.

 

In real life exceeding 4,000 ft/min in an airliner is a non issue.  Passengers will be unaware of the climb rate.  This is an unrealistic test, as they are effectively requiring you to depart in a very non-standard way to pass a check ride.  Either the person who wrote those rules does not understand flying or they know exactly the problem they are posing and seeing how well you work out the answer.

 

 

In real world ops, I use V/S every flight. When I flew heavies, we used it during accel and decel. In the DC10 we used it going from v2 plus 10 to minimum maneuver/250. You would call for climb power and vert speed 500fpm(heavy) or 1000fpm (light) at 1500ft. At min/250, we used a FLC mode called IAS hold. At 10, we used V/S again to accel to 330. On descent prior to 10,000, we used the 12 at 12 technique(set 1200fpm  at 12,000 to allow the jet to reach 250 by 10,000 clean).

 

But you would still use the rated climb thrust thoughout the climb phase, surely.  That is Bob's problem, not VS mode.  In old heavies that don't have FLC or VNAV, like the DC-10 and 747-200, the method you describe for climbing and accelreation was the best available.  IAS mode to climb at constant airspeed, VS mode to accelerate in the climb.  IAS mode with climb thrust is to all intents and purposes FLC.  But if VNAV and FLC are available, there simply isn't any point in messing about with VS during climb.  I can see the value in it for changing levels after reaching your cruise altitude in, say, a 737, but the 744 will smooth things out for you anyway by not applying rapid thrust changes.  Obviously in the bizjet world different considerations apply regarding accelerations, deck angles and so on, so as not to upset the boss and spill the champagne.   :drinks:  :smile:

[g_precentralis 191]

 

 

always wondered what the "Ц" in the sig stands for

 

Actually, it's LJ (one letter composed of L and J) in latin script, and Љ in cyrillic script, a little bit hard to pronounce. 

[G550flyer 1,008]

I wouldn't recommend using the A/T in speed mode in climb, it could create trouble for you on your check ride if the sim misbehaves or the weather throws you a curve ball.  Can you use a heavier weight?  That would result in a lower rate of climb. Otherwise the advice posted by g_precentralis (always wondered what the "Ц" in the sig stands for) to manually set lower thrust is your next best option.  You could use your practice flights to find an EPR or N1 value that will keep you comfortably below 4,000 ft/min.   That would remove your worries and you could concentrate on the flying.

 

In real life exceeding 4,000 ft/min in an airliner is a non issue.  Passengers will be unaware of the climb rate.  This is an unrealistic test, as they are effectively requiring you to depart in a very non-standard way to pass a check ride.  Either the person who wrote those rules does not understand flying or they know exactly the problem they are posing and seeing how well you work out the answer.

 

 

 

But you would still use the rated climb thrust thoughout the climb phase, surely.  That is Bob's problem, not VS mode.  In old heavies that don't have FLC or VNAV, like the DC-10 and 747-200, the method you describe for climbing and accelreation was the best available.  IAS mode to climb at constant airspeed, VS mode to accelerate in the climb.  IAS mode with climb thrust is to all intents and purposes FLC.  But if VNAV and FLC are available, there simply isn't any point in messing about with VS during climb.  I can see the value in it for changing levels after reaching your cruise altitude in, say, a 737, but the 744 will smooth things out for you anyway by not applying rapid thrust changes.  Obviously in the bizjet world different considerations apply regarding accelerations, deck angles and so on, so as not to upset the boss and spill the champagne.   :drinks:  :smile:

Well just my experiance that IAS hold and FLC isn't as good as it is in FSX.  In cargo jets, not really a big deal but with PAX it can cause a comfort factor. During FLC, it can get pitchy. Atleast the 5 and 550 is smart enough to use a lower power setting when making small altitude changes. I've never flown the 74 but the 5 and 550 has advanced avionics also. When I do use FLC, I start in V/S. I slowly increase the V/S until the engines reach max climb power. This keeps the nose from pitching up quickly as the engines go to max. At this point I hit FLC. At Mach change over, I go back to V/S.  This is what I have observed with IAS and FLC. If you hit temperature inversions, the indicated speed will increase or decrease. The nose will start pitching to recapture. Mostly the jet will over compensate with larger speed deviations leading to some G loading as it pitches up and down porpoise. When flying mach, it's even worse. I've had a guy almost stall the 10 while in IAS hold flying mach. He let it get away from him. The jet got fast and pitched up quickly. The jet then pitched over and got faster. It made another large pitch up and the speed started rolling back and thats when I took the aircraft. I had a new guy on his first 550 ride. We were on a deposition leg and he was in the left seat. We were empty and he wanted to use FLC. Said he loved it during sim training. We were light and the jet climbed at 6000fpm. He did notice as we got higher, the jet began to get pitchy. A couple of times he used vert speed to control it and re-engage FLC. After mach changer, he noticed how the jet began a small porpoise.  It continued to get worse until it went from our climb of .83 to .70. As I said I like FLC but you have to watch it and be ready to take control. I do find that it works very well in

the descent. I prefer VNAV, but in alot of the areas I fly we are usually driven off course and altitudes by ATC. 

 

In any matter, it works excellent in FSX. I was only giving him some real world techniques to help slow things down and make them more manageable. Reminds me of training flights in the KC-10. There was no reason to have all 3 engines at go around power after the touch and go. At 350K, the plane was a rocket and made manual level off difficult when only going up to 2000ft. As a custom you would pull power after the gear was up and the non flying pilot would give you vert speed 2000 to get the FD out of go around mode. This made touch n go and go arounds easier at light weights.

[ESzczesniak 128]

Well, for my two cents, I think the real take home message here is you just need to understand what your modes dow and where they may faulter.  V/S certainly has it's risk in a prolonged climb letting the airspeed decay if you're not watching and adjust the rate.  FLCH/IAS modes can have issues chasing the speed.  If you understand the shortcomings of either method and you understand what you're trying to accomplish in a given phase of flight, then it becomes a matter of dealers choice.

[kevinh 409]

I've never flown the 74 but the 5 and 550 has advanced avionics also.

 

In the 744 (and most contemporary Boeings apart from the 737 and 757) FLC begins with a demanded VS, so isn't really that different from what you do manually.  For small level changes thrust increases by only as much as necessary.  You only get to full CLB thrust if the flight level change large.

 

I haven't flown the real thing but I've used FLC in full flight sims, including the 744, many times and I haven't noticed the pitchiness with thrust change you mention, even in 737s where the thrust goes to CLB quickly.  I have seen what you talked about in the DC-10 in FSX though (in the NGX and in the BBS Airbus) where the sim got into a phugoid type motion near top of climb and rate of climb varied from 0 ft/min to about 500 ft/min.  As you said, using VS stabilised it and I could set around 300 ft/min to get to cruise altitude.  In real life that would not have been comfortable.

 

Would you really use VS in a constant airspeed climb to 10,000 ft though, allowing the A/T to control airspeed?  Surely that would require more monitoring than using FLC.

 

 

 

When flying mach, it's even worse. I've had a guy almost stall the 10 while in IAS hold flying mach. He let it get away from him

 

I wouldn't disagree with you.  Mach being affected by temperature fluctuations makes holding Mach more of a problem for the control laws than holding IAS.  That kind of real world complication is almost impossible to simulate, and therefore for a non-pilot to appreciate, in a Full Flight Simulator, let alone in FSX.

[G550flyer 1,008]

 

Would you really use VS in a constant airspeed climb to 10,000 ft though, allowing the A/T to control airspeed?  Surely that would require more monitoring than using FLC.

 

 

Our current SOP in our Gulfstreams has us call for gear up after positive rate, flaps up at 400, and 2000 vert speed at 1500 above airport(restrictions permitting). If empty or dealing with climb gradients, I FLC up and let her rip(of course we brief the pax). If I have pax, I only FLC if the jet is heavy. The weight makes it more stable pitch wise. Our aircraft can go directly to FL450 at max gross weight. The aircraft has auto speeds based on distance from the airfield when departing or arriving. I mainly use FLC when going from 250 to 300 at 10,000. I then revert back to V/S at around 28500 to 29500 when the indicator switches to mach. I do agree you have to watch the V/S. We had a warning in the DC10 about the potential of commanding more vert speed than the engines can provide. American Airlines caused this warning while returning from Europe. They stalled the jet while having a discussion about golf. Took them a moment to realize what was happening and they entered a secondary after they reset the auto slats during the stall. FLC gives the best speed protection, but not the smoothest pitch in the jets i've flown. The 5/550 will give you a power que in inverse video on the PFD when ever there isn't enough thrust for a given V/S in the climb and when there is too much vert speed to maintain indicated when descending. For the most part, 1800fpm to 2500fpm is the range you get when using FLC in the higher altitudes. I like to VNAV on the descent when ever I can. Vertical direct to altitude on the FMS makes it easier to VNAV when given step down altitudes on the fly. I use V/S 1300fpm at 13,000 to hit 10,000 at 250. This is better to keep the descent going instead of the jet going to 500fpm just prior to 10,000. Only problem with VNAV on descent is it makes altitude a priority over speed. It will increase descent to make the altitude with no regard to the increasing IAS. Doesn't happen often but you have to watch it.  I never thought passenger comfort would be such a big deal when I was flying in the military. Now I know why the airline guys constantly asked for ride reports looking for smoother air. We even configure flaps early to keep the pitch down when flying slower speeds.

[scandinavian13 5,192]

To be honest, the <4000fpm thing has me wondering if the VA knows at all what they're talking about.  If they're going to give you a low GW departure, they have to know that climb speed is going to be high based on how departures are called for in large aircraft: pitch for speed on a set thrust.  Anyone who gets upset about V/S needs to be smacked with a physics book (unless you're outclimbing the pressurization system).

 

In order to bend to their default aircraft approach to a checkride (set a V/S and manage your speed with throttle - something you're taught not to do even as low as in PPL training, except in certain circumstances), I'd follow what the others are suggesting.

 

First, I'd derate the thrust as much as possible if you're going to be using the A/T, but I'd avoid A/T unless on A/P.  Make sure to have a button for trim up and trim down to assist you in holding pitch, and to make turning slightly easier.

 

After you complete and pass the checkride, I'd honestly send them an email either linking to this thread, or perhaps even SmartCockpit to have a look at real world departure procedures.  Additionally, there are a few articles here that explain that these VA and FSPax limits on V/S are looking at the wrong issue.  Those might be worth a pointer, too.  People don't sense rate, they sense acceleration (change in rate).  A smooth pitch up to 4000+ fpm would not feel any different than a smooth pitch up to 2000 fpm.  The only real difference would be your ears popping more frequently, but it wouldn't feel like a roller coaster like so many believe.

[G550flyer 1,008]

The only issue related to high climb rate is pitch angle when using pitch and power. The DC10 and the MD80 had a max pitch for takeoff when pitching for V2+10. If I remember correctly, the MD80 was 20 degrees and the DC10-30 was 22 degrees. The big issue is losing an engine with that amount of pitch. You all ready have to trim nose down after rotation since the aircraft is trimmed to V2. If you are trimmed for a high pitch trying to maintain V+10, You have a heck of a time trying to get the nose down if you lose the engine. I did get the nose up to 35 degrees in my final flight in the 10. Co-pilot said, I bet you can't keep V2 + 10. I love a challenge. After 35 degrees nose high, I felt uncomfortable and let her accelerate plus lowered the nose.

[scandinavian13 5,192]

 

 

I did get the nose up to 35 degrees in my final flight in the 10. Co-pilot said, I bet you can't keep V2 + 10. I love a challenge. After 35 degrees nose high, I felt uncomfortable and let her accelerate plus lowered the nose.

 

Awesome.  I'm sure anyone watching enjoyed that.