Some questions for you jet drivers...

beasly

beasly

Well-Known Member
Hi all, wondering if you can verify some stuff for me that I am seeing/hearing on the jets coming into ORL--I am about 950 hours mostly prop time about 10 in a C-340A turbocharged and the gratuitous 2+ in the ATP Cessna jet (Which I thoroughly enjoyed--thanks ATP!). I.e. I am NOT a jet driver.

The gist of my question(s) is(are) do the normal stuff we do in small singles/twins translate directly to jets? I.E. is a jet more/less forgiving than a small plane in the approach phase.

Flight regime, case 1. Lose power, increase angle of attack to bleed airspeed quickly while maintaining altitude.

Yesterday on my walk, going by the ORL VFR, this Continental jet is coming in from the east making a left turn to intercept 18R at ORL and he has a "very" high angle of attack coming in (guess-timating between 10 and 20 degrees--enought to make beasly say, "Holy crap! that's a high angle of attack!") during the turn. Me, I am guessing he needs to bleed some airspeed. After the turn, you could see him slowly lower the nose, hear some power being added briefly and see it transition to a normal flight attitude followed by power being reduced. Also, in a small cessna or piper, this is perfectly safe, but your window for error is much less--so you gotta be on your toes--high angle of attack, turn, clean.

True in a jet?



Flight regime case 2. "Large power changes" during approach/intercepting glide path.

In small props, I teach this. the theory being to "minimize transition times and return to steady state flight". Take the simplest case of change in airspeed while maintaining straight and level; for a speed increase, increase power well beyond your target speed's power setting, let the a.c. transition quickly to the new airspeed and then reduce power to your new higher airspeed's power setting. Conversely, to lose airspeed, reduce power well below your target airspeed's power setting, let the airspeed bleed of quickly, overpower to stabilize at the new lower airspeed and then reduce to cruise.

I hear this especially with the bigger jets coming in--I would like to verify that it is not that effect that you get (I forget the name) when you hear a car stereo passing by at 50 and the pitch drops as it passes.

Also, you guys seem (if I am hearing correctly) move the throttle levers more quickly than we do on the pistons. (fwiw, a flight school I worked at had a "famous" 152 where the recovery from a stall went....reduce angle of attack, full throttle, pray the engine revs within 10 seconds...)


Flight regime, case 3: having fun.

I tend to see this with the smaller jets coming in. The big boys UPS, Fed-Ex , Virgin come in well established. The smaller jets (Southwest seems to do this the most) will come in off and easterly or westerly approach to final, and then wait till the last moment and then really bank it over. Beasly is like, "dang! I am jealous".

Does this happen?


Thanks for your help.

Cordially,

b.
 
beasly said:
The gist of my question(s) is(are) do the normal stuff we do in small singles/twins translate directly to jets? I.E. is a jet more/less forgiving than a small plane in the approach phase.
Click to expand...

A jet is definitely less forgiving. It's designed to go fast, therefore on the approach phase... I don't know how to describe it... but it's kind of like landing a bucket because it doesn't want to go low and slow. This effect diminishes the smaller the jet is. For example I would imagine a citation is no different than flying a king air, when it comes to maneuverability. The two things that present a challenge to the pilot with a jet, is slowing down, and getting down something which is not usually a problem on a prop unless you're 1 mile out at 3000ft agl.






beasly said:
Flight regime case 2. "Large power changes" during approach/intercepting glide path.

In small props, I teach this. the theory being to "minimize transition times and return to steady state flight". Take the simplest case of change in airspeed while maintaining straight and level; for a speed increase, increase power well beyond your target speed's power setting, let the a.c. transition quickly to the new airspeed and then reduce power to your new higher airspeed's power setting. Conversely, to lose airspeed, reduce power well below your target airspeed's power setting, let the airspeed bleed of quickly, overpower to stabilize at the new lower airspeed and then reduce to cruise.
Click to expand...



Funny, you're actually describing what you would do in a jet. Usually in a prop it doesn't really matter how you use throttles because the response of the airplane is almost instantaneous. But in a jet, there is a big lag so you have to do what you described.


By the way... I think that CAL flight, my dad might have been on it. He was going IAH to MCO yesterday.
 
beasly said:
Flight regime, case 1. Lose power, increase angle of attack to bleed airspeed quickly while maintaining altitude.

Yesterday on my walk, going by the ORL VFR, this Continental jet is coming in from the east making a left turn to intercept 18R at ORL and he has a "very" high angle of attack coming in (guess-timating between 10 and 20 degrees--enought to make beasly say, "Holy crap! that's a high angle of attack!") during the turn. Me, I am guessing he needs to bleed some airspeed. After the turn, you could see him slowly lower the nose, hear some power being added briefly and see it transition to a normal flight attitude followed by power being reduced. Also, in a small cessna or piper, this is perfectly safe, but your window for error is much less--so you gotta be on your toes--high angle of attack, turn, clean.
Click to expand...

From the sound of this, sounds like ORL approach was telling him to keep his speed up, then he had to slow down to hit the speed to drop flaps out. A jet is a jet, but it's also an airplane. Nose up, you'll lose airspeed. In the CRJ, sometimes it's beneficially to lose airpseed early so you can descend faster. Example: Chicago likes to leave you high coming into Madison, WI, who is landing on 36. Well, now you're at 11,000 ft 20 miles from the airport on a straight in if you're coming from the South. The look I used to get from the low time (not just overall, but guys not used to the airplane) when I would put the nose UP to get down faster was always interesting. Sometimes, you have to put the nose up to get down faster. The CRJ is not a big fan of descending AND slowing down at the same time.

Flight regime case 2. "Large power changes" during approach/intercepting glide path.

In small props, I teach this. the theory being to "minimize transition times and return to steady state flight". Take the simplest case of change in airspeed while maintaining straight and level; for a speed increase, increase power well beyond your target speed's power setting, let the a.c. transition quickly to the new airspeed and then reduce power to your new higher airspeed's power setting. Conversely, to lose airspeed, reduce power well below your target airspeed's power setting, let the airspeed bleed of quickly, overpower to stabilize at the new lower airspeed and then reduce to cruise.

I hear this especially with the bigger jets coming in--I would like to verify that it is not that effect that you get (I forget the name) when you hear a car stereo passing by at 50 and the pitch drops as it passes.

Also, you guys seem (if I am hearing correctly) move the throttle levers more quickly than we do on the pistons. (fwiw, a flight school I worked at had a "famous" 152 where the recovery from a stall went....reduce angle of attack, full throttle, pray the engine revs within 10 seconds...)
Click to expand...

Yes and no. There are times when you're making big changes, but times when you're not. I used to make rather large power changes in pistons on approaches, but I rarely move the thrust levers in the CRJ more than twitching them. There IS a lag in jets (as was previously mentioned), but that's why I think the best instrument in the airplane is the airspeed trend indicator. I'll use that to aid in power changes so I'm not over/under setting the thrust levers.

Flight regime, case 3: having fun.

I tend to see this with the smaller jets coming in. The big boys UPS, Fed-Ex , Virgin come in well established. The smaller jets (Southwest seems to do this the most) will come in off and easterly or westerly approach to final, and then wait till the last moment and then really bank it over. Beasly is like, "dang! I am jealous".

Does this happen?
Click to expand...


Depends. Sometimes approach will give you a late vector, and you don't have a lot of choice. I tend to avoid doing this since it has a tendency to freak out the passengers. :) Now, I like having fun, but I also try to fly the plane the same no matter if there are 50 people in the back or if it's a ferry flight that doesn't even have a flight attendant.
 
I can't speak to heavy transport aircraft with high bypass motors, but in my jet....

1) We fly our approaches at a constant 17 units AoA.....probably looks fairly significant to our prop brothers. The aircraft is very controllable in this attitude, as long as you don't require excess AoB for lineup corrections (over 30 AoB and we need lots of additional power to counter the swept wings and loss of lift)

2) Keep in mind that a lot of jets have a significant spool time compared to turboprops which give you instant power. My experience thus far is in single engine jets, but there are definitely a couple schools of thought in this area. I have found that being smooth with small power corrections is normally better than chopping the throttles a lot. You essentially end up doing the same thing, given the spool time, but it is much easier to make small corrections around a known reference power setting than to basically guess where you need to park the throttle. Worked well for me landing on the boat where there is very little margin for error, so I'd recommend this. Again, can't speak for larger aircraft with multiple engines who have the ability to walk the throttles. The way we fly though, our approaches are generally at a stabilized AoA and thus airspeed corrections are normally very small.

3) Not really sure what you are asking here.
 
hrjet said:
Funny, you're actually describing what you would do in a jet. Usually in a prop it doesn't really matter how you use throttles because the response of the airplane is almost instantaneous. But in a jet, there is a big lag so you have to do what you described.
Click to expand...

I would have to disagree on large power adjustments in jets, well at least from my experience in 135. Our passengers get a little worried when they hear large power adjustments in flight and since its all about the passengers we try to limit the amount of times we jockey the throttles. Plan ahead and like some of the other guys said, you can have the airplane on the ground safely and smoothly with small power adjustments.
 
Anyone who can say this:
"For example I would imagine a citation is no different than flying a king air, when it comes to maneuverability."

has never flown both..............

The "lag" that is being discussed is almost non-existent in newer business jet and KingAirs.
 
dustoff17 said:
Anyone who can say this:
"For example I would imagine a citation is no different than flying a king air, when it comes to maneuverability."

has never flown both..............

The "lag" that is being discussed is almost non-existent in newer business jet and KingAirs.
Click to expand...


I have been right seat in a King Air a couple of times and think of it as a "cadillac" prop plane--i.e. it behaves like the Seminole's we trained in at ATP (except for landing).

Basically, with my post, I am trying to disprove my assumptions. I think I am right, but I don't know it.

Thanks for your reply.

Cordially,

b.
 
The thing about flying jets vs. props, in the approach phase, ie. below 10,000 feet, you are always trying to -slow down- so the throttles spend a lot of time at idle, you use configuration changes to slow, from 250 to say, 210, then 180, then 150 or what your final approach speed is. If it's VFR and you've been cleared for a visual approach, you can do the entire thing with the power at idle, until you throw the big round speed brakes out when you catch the glide slope and final flaps.

When you get about 10 knts.above final approach speed, you need to start pushing the power up because it does take a few seconds for the engines to spool up. You do this smoothly, not jerky, unless you're a newbie. Now, if you have some time in the airplane, you know about where the power should be set, and what your attitude should be, so you can set it and forget it, unless it's gusting, then you have to play with it a little to stay on speed, but not like a light prop plane, because a big jet has more mass and the gusts don't immediately affect it as much as a Cessna.

You can chase sink rate with power instead of pitch, that works much better usually, but you should be able to hold a constant pitch and just tweak the power to get it stablized, then you don't have to mess with it too much, nor should you try. On the 727 and MD-11 we usually 'played' with just the middle throttle (number 2 engine, in the tail) to pick up a few knots, or lose a few, no pitch change.

Now, the SW guys are known to be cowboys, just ask that dead kid in the car or the guys working in the gas station in Burbank. They like to come in hot, with a 10kt. tailwind if it will save them 5 minutes taxi time, so you will see them jerking their noses up and down trying to bleed off speed and get configured, late, and then slam it down and max reverse to the first turnoff to the gate, asap. I cannot tell you how many times I've had to wait for them to land 'opposite direction' just so they can save a minute or two taxi time.

We get paid by the minute, they don't. So we like a nice, long, stable final, they like a slam dunk. So you will see some different 'flying styles' out there, no doubt, but in general, jets are much more stable than props, so you don't need to chase airspeed with pitch and power so much.
 
As for the initial questions:

1. High apparent AoA. Actually, it is high, particularly if flying clean, or with just slats out. Level flight with slats extended requires about 10 degrees nose up in the MD-11 or MD-10.

2. Power changes on approach. Slowing down on approach takes idle power, once on the path and configured, power has to come up substantially to hold it. I expect you're hearing that or it could also be combined with a speed requirement to the FAF, so power at idle to slow, then spool up on approach.

3. Smaller jets can get away with a bit more, although, that said, I have maneuvered an MD-11 the way you describe SW does, used to have to for HKG at the old airport, but, generally speaking, it is not the way we like to fly an airplane that might weigh near 500k on approach.
 
seagull said:
Who did you fly the MD-11 for? Autothrottles not on?
Click to expand...

The used to let us do it at Delta, "back in the day" (1996-2000). I don't like fighting with them when I'm hand flying so I always turned them off, on approach, unless it was CAT 2 or 3 of course. I think it was about 50/50 the number of guys who left them on vs. off. On the 777 we are told to always leave them on.
 
Timbo said:
The used to let us do it at Delta, "back in the day" (1996-2000). I don't like fighting with them when I'm hand flying so I always turned them off, on approach, unless it was CAT 2 or 3 of course. I think it was about 50/50 the number of guys who left them on vs. off. On the 777 we are told to always leave them on.
Click to expand...

Not arguing with turning them off, there are valid reasons for doing so, but "fighting with them"?
 
Well you know George always wants to do it -his way- and cannot anticipate my creativity in slowing at the last minute! ie. you are just coming on speed and about to drop more flaps and as the airspeed bleeds down to bug, the A/T's start to come up.

They have no idea you are about to drop more flaps, the gear, the GS is coming and you don't NEED any more power just then. On the 777 I find myself holding the throttles (excuse me, "Thrust Levers") at idle while configuring as they tend to want to come up just when I don't need any -help- from them. Once we're fully configured for landing and on speed they do a great job of holding it, smoothly, but until that point, I've got to override them with my hand.

I don't know how the Airbusses' (or is it Airbussi) guys deal with it, I hear their thurst levers don't even move, at all, until on the ground. I flew the A380 sim in Dubai for about 30 minutes and the only thing I didn't like about it was the non-moving throttles.
 
You must log in or register to reply here.
Back
Top