Can a 2 engines plane takeoff at MTOW when 1 engine quits,or only at lower weight?
All the airliners I have flown have the limiting masses expressed as weight i.e. MAUW ZFW RTOW MLW MTOW etc. because the guys that fly them are pilots and not physicists.
When I did my ATPL in the early 1990s, we spoke of MTOM - mass - not weight, as weight is a function of mass and gravitational force. So both from an engineering and physics perspective, speaking of mass is more accurate than weight which varies depending on your location (albeit by tiny amounts). I'm surprised to see that not a single one of you commenters here is using mass. Has this changed in the syllabi to use weight?
If you fly into orbit, or to the Moon, then yes there will be a huge difference between mass and weight, but I would suggest that is far too much detail in the context of the question?
Moderator
With a long enough runway, virtually all things are possible! But is it practical? - that's another thing!
In determining the maximum weight permissible for a given set of circumstances, we have to run a bunch of sums covering a range of things, including runway, obstacles, WAT, etc., etc.
For those who haven't run the AFM calculations by hand to see just what is involved it can seem that it is a bit straightforward .. ie just look up the RTOW chart or feed some numbers to the computer and read off the answer.
Just having a long runway doesn't cut the mustard unless the other bits are looked at in detail as well. Whichever of a bunch of limitations gives the lowest weight becomes the limiting case for the day ...
Are you kidding, I certainly hope so.
First off, the criteria has NO CRITERIA OEI DEP It is up to the airline to determine what the take off weight is, by looking at runway length, engine performance (which varies in time), elevation, and especially temperature.
MTOW listed, is based on engine performance (new), the airport at sea level, at 15 degrees C. Vary the engine, altitude, or temperature from 15, and it varies significantly.
Luckily, back at HQ, the performance people who are loading the ac have this sorted out for both DEP, DEP OEI, ARR, and ARR missed.
Do you also feel that you can simply use the same DEP procedure when OEI?
Are you aware that there is no criteria for OEI flightpath (see above) and that simply using what is on the chart (unless spec as OEI) offers no protection unless you can meet that climb rate, to which the pilot does not have the means to calculate?
First off, the criteria has NO CRITERIA OEI DEP It is up to the airline to determine what the take off weight is, by looking at runway length, engine performance (which varies in time), elevation, and especially temperature.
MTOW listed, is based on engine performance (new), the airport at sea level, at 15 degrees C. Vary the engine, altitude, or temperature from 15, and it varies significantly.
Luckily, back at HQ, the performance people who are loading the ac have this sorted out for both DEP, DEP OEI, ARR, and ARR missed.
Do you also feel that you can simply use the same DEP procedure when OEI?
Are you aware that there is no criteria for OEI flightpath (see above) and that simply using what is on the chart (unless spec as OEI) offers no protection unless you can meet that climb rate, to which the pilot does not have the means to calculate?
If you can't take off at MTOW, sea level, ISA, and meet the certification OEI gradient then what use is the MTOW?
As an aside. Some aircraft take-off performance calculations start from a figure that is above the max structural take-off weight so that, after allowing for performance penalties, you can still use the MTOW.
Moderator
Just as a minor side point, MTOW is not necessarily a structural limit.
For instance, the GAF N24A MTOW was OEI climb limited and, I am sure, there will be others - the updated MTOW exercise quite some years ago for the Shrike, likewise, was OEI limited.
Caveat, it was quite a while ago that I was last involved with N24 flight tests so I am presuming that things haven't changed for the model.
For instance, the GAF N24A MTOW was OEI climb limited and, I am sure, there will be others - the updated MTOW exercise quite some years ago for the Shrike, likewise, was OEI limited.
Caveat, it was quite a while ago that I was last involved with N24 flight tests so I am presuming that things haven't changed for the model.
Yes that was poorly worded. I used to have the pleasure of flying a Shrike. We had a different MTOW for VFR and IFR. Used to depart VFR then upgrade to IFR after an hour or so. Before that we used to just go IFR for the whole flight but make sure we departed in VMC. Someone decided that wasn't quite kosher.
Moderator
Someone decided that wasn't quite kosher.
Like you, I have quite a few most enjoyable hours in a bunch of Shrikes .. just like sitting out on a springboard at the local swimming pool.
I recall one flight at EN, many years ago and with a wry smile ... one of the local junior instructors came along in the RHS for the ride. In my normal manner of running checks whilst taxying along, the aircraft started wandering a little off the taxy line. Buggalugs, thinking to help out, but without discussion, stomped on the rudder to bring it back into line .. not the usual way to discover how the NWS worked. As I recall, I raised my eyebrows just a little as his face turned a bright red.
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An amusing discussion, eventually incorporating most of the important points. Save the Most Unusual circumstances, below a conservative(*) V1, STOP. Screw the brakes, just STOP. Above V1, you GO, execute MAX THRUST if necessary, fly the GA procedure and get that thing back on the ground. (Operations and maintenance will sort out the details,, later. In the instant, your ONLY responsibility is to return the airplane to terra firma and without hurting anyone.
The MTOW, distance and performance tables already include a modest fudge factor. Smart pilots double their fudge and never push the edge. They are still flying. Those who may have posed a bit too hard are dead. As is always the case, the Capt. is the ultimate judge and No Carrier will second-guess an AC who says, "No, I won't fly this leg" This is not about tanking some extra fuel - rarely questioned - but pushing the limits of the RWY and departure route. The smart girls and boys simply do not do it. Replacement crew? Smart ones ask why the priors declined and usually agree.
Even with three engines on a two engine airplane, you cannot fly it out of the sea, a lake, a river, or even a ditch! Smart pilots do not gamble.
The MTOW, distance and performance tables already include a modest fudge factor. Smart pilots double their fudge and never push the edge. They are still flying. Those who may have posed a bit too hard are dead. As is always the case, the Capt. is the ultimate judge and No Carrier will second-guess an AC who says, "No, I won't fly this leg" This is not about tanking some extra fuel - rarely questioned - but pushing the limits of the RWY and departure route. The smart girls and boys simply do not do it. Replacement crew? Smart ones ask why the priors declined and usually agree.
Even with three engines on a two engine airplane, you cannot fly it out of the sea, a lake, a river, or even a ditch! Smart pilots do not gamble.
In days past, flying Mr Boeing's Tri-motor, Eastern had lots of flights out of KFLL. The 9s were considerably shorter than presently and a rail track passed just off the end. There was a weight correction for "train on track" to account for a box car. As luck would have, I engineer'd a number of those flights, being tropical (for the US, anyway) just prior to sunset, temps were about 84-ish, with a light east wind, during the winter vacation rush, loads were heavy. It was common to have the manifest include "2 children in arms", some of the wind and a temp one degree less than the ATIS prior to pushback to get a legal RTOW. "Get the TEMP and the WIND prior to going, Captain".
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flying Mr Boeing's Tri-motor,
A gentleman's flying machine ..
There was a weight correction for "train on track"
And, in the same vein, one sometimes sees allowances made for transitory vehicles on roads and mast heights for itinerant vessels minding their own business in the waterways beyond runway head ..
A gentleman's flying machine ..
There was a weight correction for "train on track"
And, in the same vein, one sometimes sees allowances made for transitory vehicles on roads and mast heights for itinerant vessels minding their own business in the waterways beyond runway head ..
As this is not a serious conversation, it might amuse people to see what can be done if safety is not a consideration. All engine take off but runway length about half (?) the safe minimum. I love the Douglas advice to "dismantle the aircraft and ship it home".
https://www.netairspace.com/forum/vi...p?f=13&t=16698
https://www.netairspace.com/forum/vi...p?f=13&t=16698
