B757-200
Flight Crew Air Transport Pilot (ATP)
Confusion; Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Aircraft; Company Policy; Human Factors; Procedure
I entered the cockpit for preflight and the aircraft was completely shutdown; with no electrics at all. I checked the maintenance status and it was clean. I used the checklist to perform the Safety and Power On procedure: Maintenance Status/Checked; BAT Switch/ON...I reached up to turn on the battery; found the cover; lifted it and pressed. [Unfortunately;] I had pressed the RAT switch instead of the BAT switch and the RAT dropped. Certainly; inattention to detail was the paramount cause. It should be noted; however; that [most] airplanes in our fleet; have a cover over the BAT switch just like the RAT switch. Only the three merging partner aircraft do not. We routinely shut down an aircraft battery at night by lifting the cover and turning the BAT switch off. So we lift the covers a lot. So; in my carelessness; I was looking for a cover to lift to turn on the BAT and lifted the RAT instead. My aircraft that day did not have a cover over the BAT switch! We need to stress in training the similarity of the switches. Plus; we should put covers on the aircraft that do not have them.
A B757-200 Captain; electrically powering up a dead aircraft for preflight; inadvertently deployed the RAT believing the 'covered' RAT switch to have been the BAT switch.