Gate 41Things that look scary but have an explanation
What is the little fan that pops out of the aircraft?
Wait, a propeller just came out of the belly. Is that normal?
Many airliners carry a ram air turbine, or RAT: a small fan folded into the fuselage or wing root. If the aircraft ever loses its normal electric and hydraulic power, it drops into the airflow and the passing air spins it.
The spinning fan drives a small generator or pump, which keeps the most important systems running, such as the flight controls and key flight instruments. It is a backup for a backup. Losing all engines is extremely rare, and pilots practise this in the simulator.
A little deeper
The RAT deploys automatically when the aircraft detects a loss of main power, and the crew can also release it by hand. It works best at normal flying speed, and the crew keep the aircraft flying while it is out.
Deploying it is a precaution, not the end of the story. Aircraft can glide a long way, and some types also use the APU or batteries as extra backups. Details vary by aircraft type.
See it in Gate 41, in the outside view
Related questions
People involved
- Captain Imani OkaforCaptain (pilot in command)
- First Officer Mateo AlvarezFirst officer (co-pilot)
- Kenji WatanabeAircraft maintenance engineer