When Pan Am 1736 ("Clipper 1736") landed at Tenerife (about 30 minutes after KLM 4805 had arrived), the weather was clear and sunny. It was shortly after 2 p.m. local time.
Pilots and passengers diverted to Tenerife hoped they would soon be on their way to Las Palmas. Soon after Flight 1736 landed at Tenerife, the all-clear signal was given from Las Palmas. Many smaller aircraft were able to take off.
With its passengers still on board, the Pan American Clipper would also have been able to make a quick departure - except for one major problem. The KLM plane was blocking the holding area exit to the runway, and all its passengers were inside the terminal. Worse, Las Palmas no longer had an available gate for the KLM plane. It would be awhile before Flight 4805 and the 248 people on board could leave.
As the afternoon wore on, the weather deteriorated. Visibility became so bad no one in the tower could see planes on the tarmac.
Captain van Zanten was concerned. His work day would not be over when he finally arrived at Las Palmas. He and his crew needed to complete the round trip. The last leg of their flight, KLM 4806, would return to Amsterdam with passengers waiting at Las Palmas.
If KLM 4805 could not take off quickly from Tenerife, fully loaded with fuel to make the round trip, van Zanten would not be able to return the waiting Las Palmas passengers to Amsterdam that night. Under Dutch law, flight crews who exceeded their authorized duty time could be prosecuted. The pressure was on to leave immediately when the weather cleared. Meanwhile, Pan Am 1736 was hemmed in. Its pilots and passengers were most unhappy.