Aviation

[rags747]

Per Grok
Airplane manufacturers do not generally advise against taking off at maximum capacity—as long as the aircraft is within its certified weight and balance limits and environmental conditions (like runway length, elevation, and temperature) are accounted for.


Here’s how it works:


Certified Performance Standards


Manufacturers (like Boeing, Airbus, etc.) design and certify their aircraft to perform safely at maximum takeoff weight (MTOW). They publish detailed takeoff performance charts in the Aircraft Flight Manual (AFM) that pilots and operators use to calculate:

• Required runway length
• Climb performance
• V-speeds (takeoff speeds)
• Engine-out procedures

These calculations assume the aircraft is fully loaded, and are based on worst-case scenarios like hot weather or high-altitude airports.





When it’s not safe to take off at max capacity


Even though aircraft are technically capable of taking off at MTOW, airlines might reduce weight in some situations, for example:

• Short runways or high-elevation airports (e.g., Denver or La Paz): Less air density reduces lift.
• Very hot temperatures (aka “hot and high” conditions): Also reduces air density and engine performance.
• Obstacle clearance: Nearby mountains or terrain might require better climb performance.
• Regulatory limits: Noise abatement or departure path restrictions.

In such cases, operators may:

• Reduce fuel or cargo,
• Delay takeoff until cooler hours,
• Use a different runway or airport.

Summary


Airplane manufacturers fully support takeoffs at max capacity when all certified performance criteria are met. However, airlines and pilots may choose to limit the load based on real-world conditions to maintain safety margins.


Let me know if you want a real-world example, like a 737 or A320 performance under specific conditions.

 

[gtb1943]

ORLY?

“All manufacturers recommend not taking off at max. capacity?”

Provide a few examples.

I stated it; you prove me wrong

 

[gtb1943]

Per Grok
Airplane manufacturers do not generally advise against taking off at maximum capacity—as long as the aircraft is within its certified weight and balance limits and environmental conditions (like runway length, elevation, and temperature) are accounted for.


Here’s how it works:


Certified Performance Standards


Manufacturers (like Boeing, Airbus, etc.) design and certify their aircraft to perform safely at maximum takeoff weight (MTOW). They publish detailed takeoff performance charts in the Aircraft Flight Manual (AFM) that pilots and operators use to calculate:

• Required runway length
• Climb performance
• V-speeds (takeoff speeds)
• Engine-out procedures

These calculations assume the aircraft is fully loaded, and are based on worst-case scenarios like hot weather or high-altitude airports.





When it’s not safe to take off at max capacity


Even though aircraft are technically capable of taking off at MTOW, airlines might reduce weight in some situations, for example:

• Short runways or high-elevation airports (e.g., Denver or La Paz): Less air density reduces lift.
• Very hot temperatures (aka “hot and high” conditions): Also reduces air density and engine performance.
• Obstacle clearance: Nearby mountains or terrain might require better climb performance.
• Regulatory limits: Noise abatement or departure path restrictions.

In such cases, operators may:

• Reduce fuel or cargo,
• Delay takeoff until cooler hours,
• Use a different runway or airport.

Summary


Airplane manufacturers fully support takeoffs at max capacity when all certified performance criteria are met. However, airlines and pilots may choose to limit the load based on real-world conditions to maintain safety margins.


Let me know if you want a real-world example, like a 737 or A320 performance under specific conditions.

So bottom line even though it does not come out and say it, only take off under maximum load in very limited circumstances.
Which is saying its best not to.

 

[rags747]

Bottom Line:

• Airlines do take off at max capacity frequently.
• But every takeoff is evaluated individually to ensure it’s safe and within limits.
• Max capacity is the goal when it makes operational and safety sense — and it often does.

 

[CyberB0b]

For airline ops, it’s cheaper to fly at lighter weights. You can take off with de-rated thrust and every pound of weight burns more gas. Also, it limits your climb rate and maximum altitude, so you burn more fuel because you stay at lower altitudes longer. With that said, we routinely pack them to the gills for longer flights and sometimes have to boot off passengers because we’re weight restricted. It really has nothing to do with wear and tear, but it does impact wear and tear of components somewhat. tldr: we fly lighter when we can, but often fly full.

For military, the cost of the mission isn’t really a consideration.

 

[CalPolyTechnique]

For airline ops, it’s cheaper to fly at lighter weights. You can take off with de-rated thrust and every pound of weight burns more gas. Also, it limits your climb rate and maximum altitude, so you burn more fuel because you stay at lower altitudes longer. With that said, we routinely pack them to the gills for longer flights and sometimes have to boot off passengers because we’re weight restricted. It really has nothing to do with wear and tear, but it does impact wear and tear of components somewhat. tldr: we fly lighter when we can, but often fly full.

For military, the cost of the mission isn’t really a consideration.

I’m guessing the concerns over undue wear and tear have to do with landing at max. capacity but that is generally not a concern because they calculate the fuel loss for the trip? In other words, your take off weight is never the same as your landing weight i.e., you’re never landing at “max. capacity.”

 

[CyberB0b]

I’m guessing the concerns over undue wear and tear have to do with landing at max. capacity but that is generally not a concern because they calculate the fuel loss for the trip? In other words, your take off weight is never the same as your landing weight i.e., you’re never landing at “max. capacity.”

Yes, max takeoff weight is 10s of thousand pounds more than the max landing weight.

 

[CyberB0b]

The Air India preliminary is out. One of the pilots put both fuel cutoff switches into cutoff and killed both engines. The other pilot couldn’t get them restarted in time.

 

[rags747]

The Air India preliminary is out. One of the pilots put both fuel cutoff switches into cutoff and killed both engines. The other pilot couldn’t get them restarted in time.

My understanding was that those fuel cutoff switches were kind of protected from an inadvertent shutoff, Yes/No?

 

[CyberB0b]

My understanding was that those fuel cutoff switches were kind of protected from an inadvertent shutoff, Yes/No?

I believe you have to pull them out of a detent to move them.

Edit: the report says they were done one at a time, so it seems intentional.

 

[rags747]

I believe you have to pull them out of a detent to move them.

Edit: the report says they were done one at a time, so it seems intentional.

Exactly what I saw, seems u have to pull up first then toggle down. Seems like an odd mistake to make.

 

[Flamma]

Exactly what I saw, seems u have to pull up first then toggle down. Seems like an odd mistake to make.

Not a mistake. The first officer was the pilot flying. I have to wonder if the captain had any issues recently.

 

[gtb1943]

Not a mistake. The first officer was the pilot flying. I have to wonder if the captain had any issues recently.

There is no way you cut off fuel to the engines at 600 feet

not accidentally

not mistakenly

 

[Tabascocat]

I often wonder if we have lost the generation of good pilots who flew warplanes and were able to troubleshoot an aircraft. Today's pilots rely to much on automation and when automations fail, they have no clue how to respond, which has turned a once safe industry into a questionable one. Ignore me, just spitballing here…..

 

[triplets_93]

A preliminary investigation report issued by India's Aircraft Accident Investigation Bureau on Saturday said fuel control switches to the engines of the Air India flight that crashed on 12 June were moved from the "run" to the "cutoff" position moments before impact. The report did not offer any conclusions or apportion blame for the disaster.

https://www.france24.com/en/asia-pa...to-air-india-jet-engines-cut-off-before-crash

 

[Streifenkarl]

I thought it was cut off by system failure and the pilots used the buttons in order to try to get it back running again?

 

[rags747]

I thought it was cut off by system failure and the pilots used the buttons in order to try to get it back running again?

No. The cutoff switches were moved to the Off position manually just after takeoff, it’s not like a light switch, you have to do a couple of specific steps to get them in shutdown mode.

On the voice recording one of the pilots asks the other Why did you move the switches to off, the response was that I did not. Plane was found with both switches found in the run position, it looks like one engine relit while the other did not.

 

[Flamma]

I thought it was cut off by system failure and the pilots used the buttons in order to try to get it back running again?

According to the preliminary report, there wasn't a problem until fuel was cut off to both engines within a second of eachother, 7 seconds after VR. Then one pilot could be heard asking the other why he did that. The response was, I did not do so. Then one of the pilots returned the fuel switches back to the on position.

 

[Flamma]

No. The cutoff switches were moved to the Off position manually just after takeoff, it’s not like a light switch, you have to do a couple of specific steps to get them in shutdown mode.

On the voice recording one of the pilots asks the other Why did you move the switches to off, the response was that I did not. Plane was found with both switches found in the run position, it looks like one engine relit while the other did not.

Right. My guess is the pilot flying asked the question, and then put the switches back. If I remember correctly, the timeline has fuel to the first engine returned to the on position 5 seconds after it was turned off. The other was 4-5 seconds after that.

 

[CyberB0b]

I often wonder if we have lost the generation of good pilots who flew warplanes and were able to troubleshoot an aircraft. Today's pilots rely to much on automation and when automations fail, they have no clue how to respond, which has turned a once safe industry into a questionable one. Ignore me, just spitballing here…..

Aviation is safer today by a wide margin. You can look up the stats. More than half of the airline pilots in the United States are former military pilots.