MEXICO CITY (AP) -- The turbulent wake of a larger plane likely caused the crash of a government jet that killed Mexico's second-most powerful official, investigators said Friday, as they released a recording transcript showing the frantic pilots struggling to regain control of the plane.
A preliminary investigation found the pilots were slow to follow the control tower's instructions to reduce speed and appeared to be nearly one nautical mile too close behind a Boeing 767-300 on the same flight path to Mexico City's international airport, Transportation Secretary Luis Tellez said at a news conference.
He said the pilots appeared to be unfamiliar with the Learjet 45, although one had 15 years flying experience and the other had 37 years.
The pilots then swear and seem flustered about what to do.
"Alvaro what do we do, Alvaro?" Oliva says to his co-pilot, Alvaro Sanchez y Jimenez, whom officials say had more experience flying Learjets.
The co-pilot says, "Let me do it! Let me do it!"
Oliva agrees to let his co-pilot takeover, but moments later is heard swearing and then saying "Nooooo! Alvaro!"
Sanchez then says "Oh my God!" and screaming is heard in the background before the tape goes silent.
Seven seconds later, the jet smashed into rush-hour traffic in a posh Mexico City business district, killing 14, including Interior Secretary Juan Camilo Mourino, the equivalent of Mexico's vice president and one of the closest confidants of President Felipe Calderon.
Also killed was former anti-drug prosecutor Jose Luis Santiago Vasconcelos, who had been the target of at least one previous assassination plot.
Tellez's detailed account of the crash was aimed at quelling widespread rumors that the plane was brought down by powerful and increasingly violent drug cartels. The Mexican government has said from the start that the crash appeared to be an accident, but rumors of sabotage have persisted.
Tellez said officials found no explosives or evidence of alcohol or drugs in the pilots' bodies. Officials also confirmed that the plane's motors were working normally, even as the plane fell from the evening sky.
Wake turbulence was the most "solid theory," he said.
The Learjet 45 and a commercial flight from Buenos Aires were 4.15 nautical miles apart. International standards recommend at least 5 nautical miles to avoid dangerous wake turbulence - unstable air that can make it very difficult to control a plane, especially when landing.
The 7-ton Learjet would be especially vulnerable to wake turbulence produced by a 175-ton Boeing.
A video camera on a nearby building caught the plane's horrifying plunge, showing it nose-diving at a 42 degree angle, officials said. An eye witness also reported seeing the plane go "belly up," officials said.
Tellez said authorities are still conducting tests to confirm the preliminary findings.
The news conference was the first time in Mexico's aviation history that a transcript of a black box recording was made public, a continued effort to hold a transparent investigation.