Date: 201605
Local time of day: 1801-2400
Location: HOU.Airport, TX
Flight conditions: Marginal
Weather elements / visibility: Thunderstorm; Rain
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Taxi
ATC / advisory: Tower HOU
Second aircraft: Learjet 35
Reporter organization: Government
Reporter function: Ground
Second reporter function: Pilot Not Flying; Captain
Anomaly: ATC Issue All Types; Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew; Person Air Traffic Control
When detected: Taxi; In-flight
Result: Air Traffic Control Issued Advisory / Alert
Contributing factors: Human Factors; Weather
Primary problem: Human Factors

Narrative: Aircraft Y had just landed and was taxiing on taxiway Kilo to the ramp. Coordination had been made for a crossing of the parallel runways. The aircraft had just crossed runway 12L and was entering runway 12r when I thought I heard the local controller clear an aircraft for departure. (I scanned to see where my aircraft was and saw Aircraft X starting a roll down the runway.) I told the local controller that my plane was still crossing and then told the pilot to expedite his taxi. The pilot informed me he had the plane in sight. The pilot was taxiing unusually slow because of rain and slippery surfaces. He took much longer than usual to cross.The long delays the aircraft were receiving waiting for reroutes was a factor. Pilots were trying to get to their destinations and they were at runways waiting for reroutes. It became difficult to get the reroutes and pilots were getting frustrated. I would recommend that more people need to be working Center Reroute position on forecasted weather days. Too many changes and too few people led to an excessive delay for pilots.


Second narrative: After receiving a weather reroute from Hobby Tower Controller; we verified our routing and fuel burn with Dispatch and told the Tower Controller we were ready to go. Tower Controller cleared us for takeoff on Runway 12R. I taxied onto the runway and gave aircraft control to the First Officer. After he verbalized 'set takeoff thrust'; I verified the thrust setting; scanned the instruments; and set the wipers on low setting due to the light rain at the time of departure. Shortly after calling 80 knots; the First Officer exclaimed; 'What is that?' Through the rain I saw what appeared to be Aircraft Y crossing Runway 12R on Taxiway Lima; left to right. By the time I realized what it was; Aircraft Y was clear of the runway and we continued the takeoff roll. Shortly after rotation; I advised Tower that an aircraft had just crossed our runway. There was no audible response from the Controller. Moments later; as the Tower Controller switched us to Departure; he commented 'that wasn't your fault' and said something else that was inaudible.


Synopsis: Two of the Controllers and three of the pilots involved in a runway incursion at HOU describe their views of how the incident unfolded. The LR35 was cleared to cross Runway's 12L and 12R and a B737 was cleared to takeoff on Runway 12R before the LR35 was clear. Light rain and low visibility may have been a factor.