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I was just reading about the reasons why commercial aircraft will sometimes need to dump (or otherwise consume) their extra fuel. Things like decreasing landing weight, speed, reducing fire risk, etc.

It seems like the same would apply to fighter and bomber aircraft with their weapons as well.

Do these aircraft ever ditch their weapons (presumably in a disarmed state) if forced to land in an emergency? If not, why?

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    $\begingroup$ Probably depends on the emergency and what the weapon is. $\endgroup$ – SMS von der Tann Jun 13 '16 at 21:16
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    $\begingroup$ Yes they do. Even nuclear bombs $\endgroup$ – TomMcW Jun 14 '16 at 4:00
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Yes they do.

enter image description here
For example that's a failed carrier launch (YouTube). The crew jettisoned the external load (left) before they ejected (right)

It's achieved via the store release control:

For an external store emergency release there is for example a panic button in the F-4 Phantom II, a feature found on all naval aircraft in case an engine or catapult fails during launch.

That includes the external fuel tanks.

If forced to land in an emergency? If not, why?

For extreme military emergencies, which usually never end well, pilots have the option to just eject and parachute to safety.

For big bombers, like the B-52, the crew can also eject, but they can't dump fuel:

Not all Air Force aircraft have the capability to jettison fuel. The most notable example is the venerable B-52 bomber. Nevertheless, most aircraft can, and do, jettison fuel when a reduction of gross weight is required.

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Introduction

I have experience flying the A7-E Corsair off the USS Nimitz in the mid-1980's. There were typical scenarios that would require us to either jettison fuel, ordinance, or other stores. Below you will find a description of some of these scenarios.

Take off

I was in a brief with my Skipper for a night hop, and he asked me perhaps the best question any one ever asked me in a brief. I didn't have an answer, but started practicing that flight until I left the Navy. He asked, "Salt, what do you do after your take-off checklist while under tension, and right before you salute for the catapult shot?" He went on to describe what he thinks and does.

  1. Reach out look at and touch the salvo jettison button. Physically touch it.
  2. Grab the lower ejection handle.
  3. Salute and come back inside to look at the airspeed indicator. If you don't have 175 knots by the end of the cat stroke eject. No questions.

Every catapult shot I took from that day on I practiced his advice. There were 2 buttons available to jettison stores attached to the pylons under the wing. One was the select jettison, which allowed you to pick a location under the wing, and then jettison that store. The salvo jettison was a big red button close to the middle of the instrument panel, and did not discriminate. Both buttons were next to one another. All stores were ejected from the pylons. If you had a catapult shot that didn't give you enough airspeed off the bow this was an option to buy some immediate lift.

I came off Cat 2 one day and made my clearing turn. As I was cleaning up the aircraft and heading to the squadron's rendezvous point I saw something in the ocean. You know what it looks like when you take a big stone and throw it in a pond? It disappears but leaves a foot print of turbulence and bubbles on the surface of the water. Well, I looked down over the water as I was heading out and saw that kind of footprint. It was as big as an aircraft and persistent, just kind of staying there without dissipating. It looked like an aircraft had ditched, but an A6 had gone off just prior to me and used the salvo jettison getting rid of all his stores.

Tanker Duty

At times the buddy store would malfunction, and stop transferring with 500 pounds of fuel sloshing around in one of the tanks on the aircraft. You couldn't take a trap with a partially full fuel tank. The slug of fuel would shoot forward, and the tank might be ripped off the pylon. Fuel tanks were not too expensive, but the buddy store had all sorts of hardware and electronics it. Squadrons didn't like to lose these. I had a buddy store on pylon 3 and a drop tank on pylon 4.

On my last rendezvous the buddy store failed to finish transferring all the fuel in my drop tank on pylon 4 and so I said goodbye to the aircraft on my wing and called maintenance to discuss the problem. The maintenance officer got on the radio and we went over the NATOPS procedures for jettisoning the fuel tank. We found a stretch of ocean that was clear of any traffic, and after going over it once he emphasized to me, "Look at the station you selected and read it off to me." After telling him it was number 4, he finished with, "Now make sure you use select jettison and not the salvo button." I pushed the select jettison button and looked in my mirror to see the fuel tank drop away from the wing, and quickly looking in my left mirror caught the buddy store falling away as well. I swear I pushed the select jettison button, and had that image in my head. I had of course hit the salvo jettison button out routine practice of reaching for the salvo jet button every cat shot.

Air Combat

The performance characteristics of the A7-E put it at a disadvantage against fighters designed specifically for air-to-air combat. The training we received for dealing foreign fighters suggested that, once engaged ingressing to the target, we would make a defensive turn, and if the enemy got behind our wing, jettison our bombs and other stores, e.g. fuel tanks fully committing to the fight. The fuel consumption while at military power at sea level for the subsonic A7-E was around 6,000 pounds per hour, which is quite good. On the other hand, a fighter in burner, by the time it gets to behind the A7's wing line will be fuel starved. To stay in the fight with burner will require a kill within 30 seconds.

Landing & Dumping Fuel

We brought back weapons all the time to the ship. A good example is the AGM-62 Walleye, a 1,000 pound bomb with a television camera on the nose and in-flight avionics for "guiding" its flight. This was done either by the delivery aircraft, or a second aircraft in a stand-off position. We seldom dropped this weapon in practice, and would bring it back to the ship. We would launch with AIM-9's, when the fighters weren't hogging them all, and bring those back too.

The following acknowledges that there are Rules of Engagement, and within these rules and I will say this. As an attack pilot my mission was to put bombs on target, and if I didn't get the bombs there someone had to go back the next day and finish my job. The enemy would be waiting for that next strike. If for some reason I couldn't get to my target I would find a target of opportunity. Attack pilots don't bring their bombs home with them. Drop them somewhere.

As for fuel, tactical high performance aircraft from the time they take off are emergency fuel in a sense. By the time you got to the landing sequence you were almost always short on fuel. Emergency fuel is at 1,200 pounds and calling the ball at 2,500 pounds was pretty typical. That gave you 30 minutes in the pattern. A divert to another field where there was a climb en-route would eat at that reserve a bit more aggressively.

Every once in a while you might come back heavy with fuel. The maximum field landing weight was 5,000 pounds, and above this weight the procedure was to dump fuel. There were altitude restrictions on how low you could be to do this. The 5,000 pound limit was because the brakes would overheat. This would eventually cause the fusible plugs to blow releasing the pressure in the tires sometime later. This was to be avoided.

Taking the Captain to NAS North Island

While at NAS China Lake I was working with the A7E software development team on aircraft software enhancements. I would go out and test the software in the operational environment. The detachment there had an A7E Trainer, which was a two seat version of the single seater. I would at times ferry personnel where required. I got a call to take a Captain to NAS North Island and this was a quick hop. I ended up landing over weight. After dropping off my cargo I headed out to the hold short and got a call from tower informing me that my breaks were smoking. I decided to get airborne so I could get home, and if the tires blew in flight, take the gear at my home base. Left the wheels in the air stream climbing out staying below the 220 knot restriction for lowering the gear. The flight was incident free.

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    $\begingroup$ Great, real world, examples. Thank you for sharing your experiences. The one about dropping the buddy store made me cringe! $\endgroup$ – notloc Jan 15 '17 at 3:22
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    $\begingroup$ So did the Maintenance Officer. I have to smile today. I came home and stated what I believed. I pushed the select jet. The Maintenance Chief came to me after they had checked out the electronics and said they found nothing wrong. I swear I still see my finger hitting the select jettison. $\endgroup$ – Aaron Jan 15 '17 at 3:26
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Yes, military bombers do routinely dump weapons to decrease weight to reduce the hazard during an emergency landing. Sometimes dumb bombs are dumped just to save weight or as standard procure to reduce risk at landing.

In this NOAA map of the Gulf of Mexico you can see several "Explosives Dumping Areas."

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Worth noting that during WW2 bombers would usually ditch all remaining bombs before landing as the risk of one breaking loose and going off by accident was too great. This story mentions the following:

Having reached Belgium, the formation was forced to turn back because of the weather. They received a message to jettison their bombs over the Channel, as the risk of accident (and explosion) upon landing was high.

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