Definition
A pneumatic system arrangement on multi-engine turbine aircraft that allows high-pressure bleed air from one operating engine to be routed across to the other engine to spin its compressor fast enough to start it. Used in flight when an engine has shut down and needs to be relit, or on the ground when no external air cart is available.
Plain English
Using compressed air from a running engine to start a second engine that isn't yet turning. The air is piped across from one side of the aircraft to the other through shared ducting.
Context Anchor
Seen in multi-engine turbine aircraft procedures, especially engine start checklists and bleed-air system operation.
Derivation
Bleed air' is high-pressure air tapped (or 'bled off') from a turbine engine's compressor section. 'Cross' means routed from one side to the other. So a cross-bleed start literally means a start performed using bleed air sent across from the opposite engine.
Why Pilots Care
Allows engine starts without ground equipment and supports continued operation of air-driven systems if one engine is shut down.
Grounding Statement
Picture one running engine providing air pressure through a controlled valve so another engine has enough air to start.
Intuition Check
Cross-bleed is not an accidental leak between engines. It is an intentional, controlled use of compressed air from one source to serve another.
Example Sentence 1
After the right engine flamed out at cruise, the crew used a cross-bleed start to get it running again.
Example Sentence 2
With the APU inoperative, cross-bleed supplied air for the air conditioning packs during taxi.