Narrative:

Upon the captain advancing the throttles; we started to roll down the runway. An 'event' happened on the captain's side of the cockpit. I felt a liquid spray me and a loud noise. The captain said; 'you have the aircraft.' my initial thought is that he got hit in the face and eyes with something and could not see and was relinquishing control of the aircraft to me. Since we were at a low speed; below 80 KTS; and there was tons of runway; I initiated an abort. When we slowed down; the captain then took control of the aircraft and taxied it off of the runway. The event was the captain's window opening. He did feel water hit him in the face and we have no idea what it was from. We exited off of the runway; ran the checklist; and went over the brake cooling. The captain called dispatch and made an info-only write-up in the logbook. We took off without incident to our next destination.I have no idea what caused his window to open. I do think he was surprised that I initiated the abort; as the operations manual states that the captain has the ultimate authority to abort or not. I felt that at the instant he was relinquishing his command; as he told me to take the aircraft. I felt the safest thing to do was to abort under those circumstances. I feel that an action was better than no action. Also; there are places and times that going airborne and then taking care of the problem would be the proper solution.

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Original NASA ASRS Text

Title: B737 flight crew describes a rejected takeoff when the Captain's sliding window comes open at low speed and control is passed to the First Officer.

Narrative: Upon the Captain advancing the throttles; we started to roll down the runway. An 'event' happened on the Captain's side of the cockpit. I felt a liquid spray me and a loud noise. The Captain said; 'You have the aircraft.' My initial thought is that he got hit in the face and eyes with something and could not see and was relinquishing control of the aircraft to me. Since we were at a low speed; below 80 KTS; and there was tons of runway; I initiated an abort. When we slowed down; the Captain then took control of the aircraft and taxied it off of the runway. The event was the Captain's window opening. He did feel water hit him in the face and we have no idea what it was from. We exited off of the runway; ran the checklist; and went over the brake cooling. The Captain called Dispatch and made an Info-Only write-up in the logbook. We took off without incident to our next destination.I have no idea what caused his window to open. I do think he was surprised that I initiated the abort; as the Operations Manual states that the Captain has the ultimate authority to abort or not. I felt that at the instant he was relinquishing his command; as he told me to take the aircraft. I felt the safest thing to do was to abort under those circumstances. I feel that an action was better than no action. Also; there are places and times that going airborne and then taking care of the problem would be the proper solution.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.