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convair880mfan
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If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 3:51 am

A friend told me awhile back that the FAA fined Southwest Airlines for sometimes taking off too heavy or with an incorrect center of gravity. Not sure what he said was true. I was just wondering what the airlines do when an aircraft is illegal for takeoff given conditions especially when it is not legal to weight due to existing conditions? Is the flight perhaps delayed until conditions improve? Can a flight be cancelled?

On a flight on an American Airlines 727-200 with few passengers once, we were instructed to move from our assigned seats. I imagine this was for CG reasons but never found out why? Do airlines ever deny boarding to passengers when a full passenger load would compromise the safety of a takeoff or do they reduce the cargo load? I can't imagine they would mess with the fuel load. Take a 115 degree day and a plane is too heavy.

Does anyone remember a case when an airline had to call Boeing for help when outside air temps went off the charts?
 
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Starlionblue
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 3:59 am

There are several possibilities before you remove paylod.

- If possible, ask for a more favourable runway.
- Be very precise with the takeoff wind calculations.
- If possible, wait until the temperature decreases. Even one degree can make a difference.
- If possible, shift the CG to a more optimal position for fuel-efficiency.

We "mess with the fuel load" all the time. For example, do we really need the standard twenty-minute taxi fuel if we are expecting a five-minute taxi? Also, if you reduce payload you can reduce the fuel load.

In some case, though, you need to offload stuff. Pax bags would probably be offloaded first, then pax, thet cargo. Certainly, boarding can be denied for weight reasons.

When you needed to move to other seats, it was probably for CG reasons.
 
convair880mfan
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 4:27 am

Thank-you Starlionblue.
 
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Starlionblue
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 9:18 am

To expand on "messing with the fuel load", we're not always trying to find every last kg. Shaving off some taxi fuel is only something we might consider if we are close to the limit. In the majority of cases, we calculate the final fuel based on the final weight and check that we are within limits.
 
extender
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 11:36 am

Change the flight crew...
 
Woodreau
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 1:04 pm

Ive had several instances when we could not take off due to the aircraft exceeding the max runway takeoff limit.

Most of them were solved by just switching runways. Only once have I had to offload payload.

In that instance out of Denver, the OAT was to the point where we already denied boarding to 12 passengers before the boarding process began. After boarding complete, we determined that the plane was still overweight by 1200 lbs. or overweight by 6 passengers. I switched the runway from 34R (the 12,000ft runway) to 34L (the 16,000ft runway). It didn't matter we were still 1200lbs overweight, we were second-segment climb limited. It wasn't the runway. The gate agent came onboard and asked for 6 volunteers to deplane. But obviously now that the passengers were on the plane, no one is going to volunteer to get off. After getting no takers, operations decided to off load 40 bags and we pushed off the gate leaving 40 bags in Denver. (after we got in the air, our FA called up, one of the pax is asking about why they saw bags being unloaded off the plane?.... well... uh.... yeah... )

Recently in June 2021, the FAA changed the standard weights again. In 2000, the standard weight of a passenger was 170/175lbs. As a result of the Charlotte crash, standard weights for passengers increased to 190/195lbs. and in 2021, the FAA mandated each airline to survey its passengers to establish a new average passenger weight instead of using 190/195.

Flight crew had to get our rollerboards and flight kit bags "sampled" during Spring 2021.

Each airline had to submit a plan to the FAA on how it was going to establish a new standard passenger weight.

So now my airline uses 200/205lbs for each passenger. I imagine as time goes on, will pax weights continue to climb?

10 lbs doesn't seem like much, but a full plane for my airline using 190lbs per pax has a pax payload of 43,320lbs not including bags cargo and fuel.
With the new rules a full plane using 200lbs per pax now has a pax payload of 45,600lbs not including bags cargo and fuel.

Our standard bag weight has increased as well from 30lbs a bag to 37lbs a bag (for bags that weigh less than 50lbs), and heavy bags (bags that weigh 50-100lbs) increasing from 50lbs to 58lbs.

Where this will impact things are at the regional airlines, where the regional jets were already weight limited with the 190/195lbs, they'll be further weight limited with whatever new weights each regional airline comes up with.

At the regional airline I worked with, bag weights could be a magic trick...
Say you pack a roller board and weigh it at home, it weigh 45lbs... you bring it to the airport and check the bag at the ticket counter. It goes to the ramp, gets loaded in the cargo compartment and now the bag weighs "30lbs"
You decided not to check it at the counter, you bring it to the gate, you decided to gate check the bag, It goes to the ramp, gets loaded into the cargo compartment and now the bag weighs "20lbs"
You decide not to gate check it and you bring it onboard the aircraft and stick it in the overhead bin... the bag weighs "nothing" is included as part of the 190lb passenger weight.
Never mind that in all 3 scenarios, the 45lb bag is onboard the aircraft having three different weights depending on where you put it.

So at the first shady regional airline i worked at, if we were overloaded, the bags came out of the cargo comparment and into the cabin where they weigh "0lbs"
 
LH707330
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 3:48 pm

I've seen a couple of these scenarios. Coming out of Denver on an unseasonably warm day, they needed to bump 6 people on an E175. Nobody went for the $250 that they first offered, so they increased the bid to $1000 and they had enough takers. IMHO that sort of auction should be the standard.

The bag weight nonsense does seem pretty dodgy. That sort of normalization of deviation will eventually lead to another regional plane going into the weeds.

Regarding the temps being off the charts, that was an issue in Phoenix a while back on the CRJ, IINM their charts go to 47* and the temp was 48*. Although the aircraft was most likely flyable in that condition (extrapolate the values one degree further out), it wasn't authorized, because that was not a certified and approved configuration and condition.
 
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dennypayne
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 4:38 pm

How proactive is dispatch and/or scheduling about all of this? Do they sell less seats in PHX in the summer or do they just leave it up to the pilots and gate agents to sort it all out on the day of?
 
LH707330
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 10:29 pm

dennypayne wrote:
How proactive is dispatch and/or scheduling about all of this? Do they sell less seats in PHX in the summer or do they just leave it up to the pilots and gate agents to sort it all out on the day of?

My guess is that the competent outfits plan on a likely set of conditions based on history and forecasts (e.g. "PHX is usually 45* 80% of the time, so that means we can plan on X payload") and then have some day-of buffer like cargo or standby pax that they can bump or take depending on how it looks. If it's a serious weather outlier (e.g. the PNW heatwave in June or the CRJ over-temp in PHX) then they probably have to bump more pax and offer more waivers. As the climate changes and we see more extreme weather, expect more of these sorts of thing to pop up.
 
N1120A
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Tue Aug 17, 2021 11:00 pm

dennypayne wrote:
How proactive is dispatch and/or scheduling about all of this? Do they sell less seats in PHX in the summer or do they just leave it up to the pilots and gate agents to sort it all out on the day of?


PHX isn't THAT bad, thanks to being at a relatively low altitude MSL. Even at 50 degrees C, which even Phoenix doesn't hit that often, at 29.92, the density altitude would be 5230 feet. That is not an issue for most modern turbines. Indeed, I think they'd be keeping people off the ramp due to extreme heat before needing to limit aircraft weights.

Now, at airports like DEN or ABQ, I'd imagine the airlines are looking at this when the TAF and MOS come out and will proactively offer bumps - especially in the post-Dao era.
 
RetiredWeasel
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Wed Aug 18, 2021 12:59 am

Ancient info here, but flying 727's into Phoenix back in the early 90's: in 90 or 91, the summer temp went over 120 degrees F. Our charts only went to 120. Couldn't takeoff. Company got on the horn to Boeing and they started faxing the needed data to dispatch then down to the crews. The first day we were just canceled because we ran out of duty time even though the night temp cooled some. With the new data, took off the next day. Back in those days, we used paper charts in the 'weight manual' which was about 4" thick and covered every runway we used in the US.
 
FlyHossD
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Wed Aug 18, 2021 4:18 am

N1120A wrote:
dennypayne wrote:
How proactive is dispatch and/or scheduling about all of this? Do they sell less seats in PHX in the summer or do they just leave it up to the pilots and gate agents to sort it all out on the day of?


PHX isn't THAT bad, thanks to being at a relatively low altitude MSL. Even at 50 degrees C, which even Phoenix doesn't hit that often, at 29.92, the density altitude would be 5230 feet. That is not an issue for most modern turbines. Indeed, I think they'd be keeping people off the ramp due to extreme heat before needing to limit aircraft weights.

Now, at airports like DEN or ABQ, I'd imagine the airlines are looking at this when the TAF and MOS come out and will proactively offer bumps - especially in the post-Dao era.


Good responses above. But to further complicate matters, on a hot day in DEN, maximum tire speed was a real issue, too.
 
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9MMPQ
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Thu Aug 19, 2021 9:15 pm

Starlionblue wrote:
There are several possibilities before you remove payload.


If limited by runway or weather conditions another trick on the B747/B777 is to turn off the (airconditioning) packs before take off which slightly improves the take off performance. The packs would be turned on again a bit further on in the climb out. This could bring us another 1000 to 1200 kgs of allowable payload but all at the crew's discretion. Some didn't bother but others were only to happy to help get as much out as possible.

There are a lot of variables but it's very intresting to try & put all the puzzle pieces together & get all of the performance out of an aircraft if you are having to deal with limitations.
 
RetiredWeasel
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Thu Aug 19, 2021 9:40 pm

Not mentioned is defueling. Time consuming procedure, but I remember having it done on a 747-200 once or twice. Can't remember how they did it, but think a mechanic came up to the cockpit and used the boost pumps and the dump manifold, but not sure. Think because it was done, a fuel stop was added in ANC which is another option on long hauls.
 
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Starlionblue
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Fri Aug 20, 2021 12:51 am

9MMPQ wrote:
Starlionblue wrote:
There are several possibilities before you remove payload.


If limited by runway or weather conditions another trick on the B747/B777 is to turn off the (airconditioning) packs before take off which slightly improves the take off performance. The packs would be turned on again a bit further on in the climb out. This could bring us another 1000 to 1200 kgs of allowable payload but all at the crew's discretion. Some didn't bother but others were only to happy to help get as much out as possible.

There are a lot of variables but it's very intresting to try & put all the puzzle pieces together & get all of the performance out of an aircraft if you are having to deal with limitations.


Completely forgot to mention packs off, but I think of it more as a "standard" option since it goes right in the calculation and there's no need to coordinate with anyone. :)



RetiredWeasel wrote:
Not mentioned is defueling. Time consuming procedure, but I remember having it done on a 747-200 once or twice. Can't remember how they did it, but think a mechanic came up to the cockpit and used the boost pumps and the dump manifold, but not sure. Think because it was done, a fuel stop was added in ANC which is another option on long hauls.


Not only time consuming but a planning headache since the fuel can then only be used in another company aircraft.
 
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9MMPQ
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Fri Aug 20, 2021 8:46 pm

Starlionblue wrote:
Completely forgot to mention packs off, but I think of it more as a "standard" option since it goes right in the calculation and there's no need to coordinate with anyone. :)


Different companies, different strokes. It was never a standard inclusion in our flightplan but was a part of the final performance calculations. We could always ask crews to take it into consideration if we were really getting up there on the numbers. Most were happy to go for it. I've even had a Captain who would offer it every time he came through even though he had not seen the paperwork yet.

Good times, it was always nice to add the finishing touches to it as a team.
 
bigb
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Fri Aug 20, 2021 11:41 pm

Packs off if needed or in the event fuel is needed for an alternate, blocks seats.
 
Canuck600
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Re: If an airliner is too heavy for takeoff due to conditions, how is it lightened? Remove pax? cargo?

Mon Aug 23, 2021 6:51 pm

In the air tanker firefighting world, I know they will defuel before removing retardant from the aircraft, at least here in British Columbia, Canada.

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