Also, if FS2004 is anything like FSX, if you are in reverse thrust mode, trying to add more thrust with the thrust levers will cause the reversers to reset to flight mode.

Look in the aircraft.cfg file and look for an entry like "min throttle limit" in the ENGINES sections. making it a larger MINUS number will give more reverse thrust

Thanks , i cant remember the airfeild , old screenshot ...sorry 

Andy,   Yes, I use FS9. Reverse Thrust would be used once the Airplane is on the Ground, not during Flight. Typically you would hold the F2 Key down to initiate Reverse Thrust.  The King Air I noted only as an example Airplane because it uses the PT6 Turboprop engine, which you can use Reverse Thrust to slow the Airplane down on the Landing Roll. When the Airplane is at a dead stop, holding down the F2 Key will make the Airplane start to roll backwards. I do not know if this Feature is replicated in Jet Aircraft; I'll have to give it a try and see what happens, and look at the External View to see if the Thrust Reversers are Modeled in the Aircraft itself and actually move.

very nice screenshots 

People also try to powerback in turboprops.   In a King Air there is a real risk of a compressor stall to the engine. That would be a very pricey error, when in real life it is very easy step outside and attach the tow bar to push the aircraft backwards.   And for those who try to reverse props in a dive, attempting to get into an airport with to short of a runway (NOT A GOOD IDEA), the King Air will not reverse props above 95kt. You would get a Prop Rev Not Ready annunciator light.  

Though reverse thrust is primarily to slow the aircraft on landing and to shorten the landing roll, in real life there was a time when many jets would use reverse thrust to back from the gate (powerback), but to the best of my knowledge that hasn't been used for many years, at least partially because of the risk of FOD (Foreign Object Damage) from debris kicked up, as well as the fact that it uses a lot of fuel, among other reasons.

I'm not aware of reverse thrust used for backwards motion.  It is used as a brake to slow the plane to taxi speed more quickly.

Thanks for your reply. I tried the reverse option as you described. I tried with a Dreamwings Embraer 170 on the ground. I could hear the reverse engine sounds but there was no backwards movement of the aircraft. Do you still use Fs9? If you do then if you go to the assignments entry for Decrease engine rapidly (F2 as you stated). You should see a slider that can be set to the right,middle,or left, it's that slider setting Iam after. I reset my custom assignments to the default and there the slider (for want of a better description)is to the left.I assume that has to be the correct choice. Anyway I reset my own  custom settings for assignments (something i have done many times over the years so takes little time and will leave it at that) Thanks for your reply. I will take time to monitor what happens on landing and see what occurs. Just to finish Iam not sure whether on landing you should tap F2 rapidly or just the once to instigate reverse thrust. I will continue to experiment as I have done for many centuries with all things Fs9   Cheers  Andy  

Sunclass Airlines |  Airbus A330-223 | OY-VKF |  Faro Intl. Airport, Portugal | LPFR / FAO |  Vacation Time is over, so people fly home... - off to Copenhagen. 

Then I guess I better not mention screwing up the CPU too. DOH! Being clumsy= $$$. Self-inflicted wounds still hurt - the mind, the ego and the wallet - lol Yet I do NOT regret taking on the challenge of this first-time full build. I keep telling myself - "It's all about the journey, not the destination."... but I sure will be glad when I come to a successful conclusion.