Simviation Forum - Just curious

Apr 21^st, 2004 at 8:23pm

Bruce Offline
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Lets use the 737-400 for example....on the take off roll You rotate after reaching a speed of 140 if i am correct...In the real world what happen if the pilot is still rolling after rotation speed is reach. just curious.
thanks Bruce

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Reply #1 - Apr 22^nd, 2004 at 9:08am

garymbuska Offline
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Praying comes to mind. It is possiable to put to much weight in the front of any plane to where even if you were on the salt flats it will never get airborne.
Most of the airlines have weight gauges in them so a pilot knows how much weight is on board but it does not tell him where the weight is at. A pilot gets a Weight & Data sheet just before he pushes back from the gate. The load desk operator is responable to make sure that these weights are correct. I used to be a load desk operator for delta airlines at KJAX and we had a good scare one day. We had a B727 going to KDFW and because of the weather problem in dallas it had to have a full fuel load which means that there is not much weight left before it reaches what is called MTOW or maximum take off weight. And the last place you want weight is in the first bin or up front at the nose. The palne had pushed back and was at the runway about to take off when some one came up to me and said oh by the way he had put 15 bags in bin 1 at the last min. Both me a the ramp supervisor freaked I started to run for the radio to let the pilot know but it was to late as he was already on roll for take off all we could do was to watch and pray it got airborn because we know that it was going to be close. The plane used almost all of the 10,000 foot runway before it got airborn and when he called in to report his out and off times I asked him if he had a problem taking off and his answer was he started to see his life flash before him he did not think he was going to make it and wante to know what happened. I told him about the last min bags that we did not know about until he was on the runway. All he had to say was thank god for the long runway.

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Reply #2 - Apr 22^nd, 2004 at 10:21am

Ridge Offline
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Gotta hate those idiots!!

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Reply #3 - Apr 22^nd, 2004 at 8:26pm

Bruce Offline
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Thanks Gary for the info. actully what i was eluding to is say all conditions are ok such as enough runway right weight in the right place but you are rolling say 200mph or higher can you still rotate. the reason why i ask is a lot of time while i am rolling i might be looking at the scenery lol and by then i am up to 180 or even 200 but i still up. I was just curious if its ok.

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Reply #4 - Apr 25^th, 2004 at 8:24am

Lux13 Offline
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Hi!
Nothing particular happens until you reach the maximum tyres speed........!!!!After that speed,your tyres aren't guaranteed......they could exlode!!!
But if you are below that speed,you just have more lift.
Cheers!

Thank God for let me fly!

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Reply #5 - May 26^th, 2004 at 6:04pm

Staiduk Offline
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Thanks for that Gary - the big aircraft look so big and powerful its often easy to forget how precisely balanced an aircraft is in regards to weight. Whenever I take people up in my whoppin' huge 172 (ok, ok, no laughing, please... Wink

) they sometimes think I'm being a bit stuffy or dictatorial when I insist on deciding who sits where.
A question though: You mentioned "And the last place you want weight is in the first bin or up front at the nose." Given the choice; (admittedly; a choice between Scylla and Charybdis) if I somehow attempt a takeoff above MTOW (haven't yet; but you never know what the future holds); I'd rather have the weight forward; rather than too far aft - we all know what having an aft CG does to stability. Is that less important in an airliner; or more precisely is an airliner built so that a critically aft CG more difficult to achieve than a critically forward CG?
Thanx!

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Reply #6 - May 26^th, 2004 at 9:06pm

Nexus Offline
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Staiduk it depends on the aircraft.
Obviously aft mounted engine aircrafts are more sensible to CG changes. The concentration of weight at the rear makes it harder to keep the balance with varying passenger and fuel loads.

On the contrary, the 737's rear cargo hold is capable of holding more luggage than the forward hold.
I'd say it's somewhat easier to maintain a 'green' takeoff CG with wing mounted enginge types?

Garymbuska, you have any more interesting stoires to share? I'm all ears

« Last Edit: May 26^th, 2004 at 10:24pm by Nexus »

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Reply #7 - May 26^th, 2004 at 9:49pm

tsunami_KNUW Offline
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Life is good.
Oak Harbor, Washington

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Quote:

Praying comes to mind. It is possiable to put to much weight in the front of any plane to where even if you were on the salt flats it will never get airborne.
Most of the airlines have weight gauges in them so a pilot knows how much weight is on board but it does not tell him where the weight is at. A pilot gets a Weight & Data sheet just before he pushes back from the gate. The load desk operator is responable to make sure that these weights are correct. I used to be a load desk operator for delta airlines at KJAX and we had a good scare one day. We had a B727 going to KDFW and because of the weather problem in dallas it had to have a full fuel load which means that there is not much weight left before it reaches what is called MTOW or maximum take off weight. And the last place you want weight is in the first bin or up front at the nose. The palne had pushed back and was at the runway about to take off when some one came up to me and said oh by the way he had put 15 bags in bin 1 at the last min. Both me a the ramp supervisor freaked I started to run for the radio to let the pilot know but it was to late as he was already on roll for take off all we could do was to watch and pray it got airborn because we know that it was going to be close. The plane used almost all of the 10,000 foot runway before it got airborn and when he called in to report his out and off times I asked him if he had a problem taking off and his answer was he started to see his life flash before him he did not think he was going to make it and wante to know what happened. I told him about the last min bags that we did not know about until he was on the runway. All he had to say was thank god for the long runway.

What a moment! Shocked

&&Home Airport: NAS Whidbey Island (KNUW)-Oak Harbor Airpark (76S)&&Current FS Location: Seoul/Incheon, South Korea

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Reply #8 - May 26^th, 2004 at 11:24pm

OTTOL Offline
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Quote:

Lets use the 737-400 for example....on the take off roll You rotate after reaching a speed of 140 if i am correct...In the real world what happen if the pilot is still rolling after rotation speed is reach. just curious.
thanks Bruce

In large aircraft and in JET aircraft, period, the rotation speed is different every time. This speed is dependent on weight, temperature and altitude(Density). Rotation speed is just a reference. It is used as a reference for the pilot to begin applying back pressure to the yoke. At this speed the aircraft should be rotated about it's lateral axis. If the aircraft is not "pitching up" at this speed, it does not mean that something is wrong.
V1 is a much more critical speed for pilots in Jet aircraft. If an engine fails before V1, the takeoff must be aborted. If a failure occurs AFTER V1, the pilot must continue the takeoff, REGARDLESS of how much runway he thinks is remaining to stop the aircraft.

.....so I loaded up the plane and moved to Middle-EEEE..........OIL..that is......

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Reply #9 - May 27^th, 2004 at 12:01am

Nexus Offline
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The greater of two evils...

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Quote:

...If a failure occurs AFTER V1, the pilot must continue the takeoff, REGARDLESS of how much runway he thinks is remaining to stop the aircraft.

But what if the engine failure also led to flight control malfunctions. Would you still continue the take off?

I'd rather risk an overun of the runway than dealing with an uncontrollable aircraft ???

Any ideas OTTOL?

Btw V1 in larger jets is also affected by flap setting, runway length, dry/wet, wind speed/direction and CG. So it is a subject to change allright

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Reply #10 - May 27^th, 2004 at 12:27am

OTTOL Offline
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Fintas, Kuwait (OKBK)

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The thread in the History section about the DC10 crash is the worst case scenario of this kind of failure but a textbook example nonetheless. If you read the transcript, it states that the engine broke off the aircraft while it was still rolling down the runway. Unfortunately the hydraulics and ultimately the flight controls were affected by the catastrophic failure. The crew was simply doing what they were trained to do. They were ABOVE V1, so they continued into the air.
Given the odds, I would still choose to take the plane into the air. Most importantly, because that is what we train to do many 100's of times, over and over again and secondly, the number of pilots who have died after attempting to abort a takeoff AFTER V1 is much greater than the number who have suffered a catastrophic failure POST V1.
Before every takeoff, as a Captain, I must brief my crew on the takeoff procedure. It's a "broken record" but it must be done. There have been circumstances where I have been faced with an extra long runway and good ambient conditions and at the crucial point of V1 I have had the fleeting "what if" thought. My answer to myself is the same. Travelling down the runway at 150kts is no time to be indecisive and speculate......."Ok, I know we briefed "after V1 it's an in flight emergency", just as we have done 1000's of times before but what if I DO try and stop this time............."

Good points on the OTHER factors relating to V-speeds. Your knowledge impresses me as always. When are you going to apply that to some REAL aircraft training?

.....so I loaded up the plane and moved to Middle-EEEE..........OIL..that is......

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Reply #11 - May 27^th, 2004 at 7:43am

Nexus Offline
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The greater of two evils...

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Thanks for the in-depth explanation OTTOL. Great read!

I've heard of that DC10 accident, wasn't it during the early years of that aircraft type? Lots of problems it had in the beginning

When am I going to start aviation training, it's (as always) a question of money. I'm currently working night shift just to get a better pay check. Hopefully I'm able to start next year...I'm itching to go already

I'm planning to move to the U.S permanently and have a career there. What's uour thoughts...any problems in getting a job just because I'm European?

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Reply #12 - May 27^th, 2004 at 8:10am

Craig. Offline
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Birmingham

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nexus, as you know i am also looking into a permanent move to the US. If your serious about it. Apply for the required visa early. Unless you have a guarenteed job offer, your Green card process could take upwards of two years. If your from a country in the lottery list, then apply for that, you could win a green card and its done quickly. If neither of those work you can go as a student, you would have 2 years to complete your flight training, and would be able to work as a flight instructor for the time you are there. If you can proove yourself in that time then you will stand the chance of an employment visa. If not the only other ways would be marrying someone from there, or having immediate from The US.

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