Powerback
Powerback is used by aircraft to reverse using the power of their engines, In Europe only propeller aircraft tend to use powerbacks as a means of reversing, while in the USA some larger jet aircraft also perform powerbacks.
While many aircraft are physically capable of performing powerbacks, many companies impose restrictions on the practice, mainly due to the risk of foreign object damage from debris propelled into the air. Small metal objects are particularly dangerous as they can be propelled into terminal windows, employees on the ground or even the aircraft itself. Northwest Airlines' fleet of DC-9 aircraft used to commonly utilize powerback operations at certain airports, however the airline discontinued the practice in 2005 citing the need to conserve fuel.
In addition, in the United States, restrictions on powerbacks are enforced by the FAA, and the local aviation officials. Only certain gates at certain airports are approved for powerbacks, and are usually placarded as such. Many airlines impose stricter safety procedures for powerbacks, which often include disallowing a powerback under certain environmental conditions, such as rain or snow.