Checked on the net, but cant find the answer I am looking for.

Say your plane gets redirected to a closer airport BEFORE taking off.

How much fuel can be burned by reeving the engine, before the plane has to go back and have the fuel dumped somewhere.

and where does the plane go for that to happen.

I have heard it can take 2 to 3 hours to dump excess fuel at the airport

Not a real-world airline pilot, but that hasn't stopped me in the past, so here goes.

38 minutes ago, Ron Lefebvre said:

Say your plane gets redirected to a closer airport BEFORE taking off.

I think it would be pretty rare for this to happen after the plane has already been fueled but before takeoff. You mean redirected by the company? Because the originally planned destination is not usable for some reason?

39 minutes ago, Ron Lefebvre said:

How much fuel can be burned by reeving the engine, before the plane has to go back and have the fuel dumped somewhere.

Do you mean on the ground or in the air?

If the current fuel load would have you arriving at the new destination over max landing weight, I think the most typical thing would be to defuel the airplane before you take off. At today's fuel prices, you wouldn't want to simply burn the fuel.

If you couldn't defuel, I don't think you'd want to do a higher-power run on the ground. If you get to your destination and you're still over MLW, I guess you could ask to hold and lower the gear to increase the drag / fuel burn. You could of course also dump the fuel, but I believe many places want you to go out over uninhabited areas to do that.

Purely out of interest, do you have a RW example of this? I can’t think when this would actually happen… the flight would just cancel. 
 

Fire up MSFS and give it a go and track your fuel burn on the ground. I’d imagine it would be minor in the grand scheme of things. 
 

A lot of the time to offload fuel would be eaten up by finding a gate, personnel, paperwork etc, so the total time difference between offloading 1 or 5 tonnes I’d assume would be marginal. 

Yes redirected by the company on the ground.

I just though with all the airline delays, a plane fully loaded with fuel could be redirected to a shorter route.

Probably never happens.

 

1 hour ago, Ron Lefebvre said:

Checked on the net, but cant find the answer I am looking for.

Say your plane gets redirected to a closer airport BEFORE taking off.

How much fuel can be burned by reeving the engine, before the plane has to go back and have the fuel dumped somewhere.

and where does the plane go for that to happen.

I have heard it can take 2 to 3 hours to dump excess fuel at the airport

Good question. Yes, this situation can and does happen. It all depends on where you are when this happens and how much gas you need to get rid of. I will give you three situations that happened to me and how we dealt with it.

1. I was in a DC10 at PHNL and heard on ATIS that the reef runway was out of service due to barrier maintenance. Checked the NOTAMs and yeah, the monthly two hour closure happened to be scheduled for this morning. First, we called ATC to see if they could waive it. They referred us to the USAF. We call base ops to have it waived and they referred us back to the FAA. After various back and forth sessions, they finally both said, hey, it's scheduled, deal with it. Now, we were 20,000 pounds of fuel too heavy for the other runway due to climb requirements If I remember right. So, someone told the PIC that we should defuel. I advised against it knowing how long it can take to find a defuel truck to take that much fuel and then get it done. I advised that we should wait the two hours and depart with the current fuel load. We were only going to Cali, so not a big deal. The PIC got antsy and wanted to defuel. By the time we were defueled and finished, the runway we originally wanted was open. We should have waited as I advised. You definitely have to weigh options to see what best works.

2. We are in a GIII and the other guy watching the fuel got distracted and allowed the jet to fill all the way up😑. I was doing the walk around and the truck driver gave me the thumbs up saying we were done. I go inside and the other pilot was not in the seat🤔. The tanks were full and he said he was distracted and forgot we were fueling. So the problem we had was the next day leg was short and we would arrive 3000 pounds over max landing weight. So, we called for an engine start and gently bumped the throttles to 1000 pounds per hour. Took about an hour and a half to get down to weight and then we shut down and called it a day. At times when the fuel to lose is under 3000 pounds, it's quicker to run engines and burn for an hour or so. The defuel rate is slow, and not the same speed as coming on. So in most cases, you can burn it off faster than you can offload it.

3. I was in a KC10 and flying into this place that didn't have fuel during the war. In this case, we were tankering fuel, meaning take what you need to get there and back. This was a regular occurrence and at times you would arrive over max landing weight. In situations like this, you have two options. One, you build in a timing triangle that will take you out of the way off your route to burn more fuel. The second option is to go into holding on arrival and fly a faster speed. You can even do a combination of both options. I would even do this for timing. Sometimes you will have pomp and circumstance on arrival and they are not ready for you yet. In that case, they give you an arrival and you build a timing triangle to arrive right at that moment.

I hope this helps with your question.

2 hours ago, G550flyer said:

I hope this helps with your question.

Great tales thanks for sharing!

I'll quit my idea of flying the new route at 5000ft, gear and flaps down with packs on max then 😄

47 minutes ago, sloppysmusic said:

I'll quit my idea of flying the new route at 5000ft, gear and flaps down with packs on max then 😄

🤣, sometimes we have to do what we have to do🤣