Russian plane crash in Egypt: It's too early to determine cause, officials say

Flight 9268 was on its way from the Egyptian resort of Sharm el-Sheikh to St. Petersburg early Saturday when it dropped off radar about 23 minutes into the flight, Egyptian officials say.

Air traffic controllers apparently didn't receive any distress calls. 

"There was nothing abnormal before the plane crash," Egyptian Civil Aviation Minister Hossam Kamel said Saturday. "It suddenly disappeared from the radar."

The website Flightradar24, which tracks aircraft around the world, said it had received data from the Russian plane suggesting sharp changes in altitude and a dramatic decrease in ground speed before the signal was lost. 

A U.S. satellite that was over Sinai at the time of the crash detected a heat flash, according to a U.S. official directly familiar with the latest information in the investigation. U.S. intelligence and military officials are analyzing the data to determine whether the flash occurred in midair or on the ground and what that can tell them about what happened to the plane, the official said.

Analysts say heat flashes could be tied to a range of possibilities: a missile firing, a bomb blast, a malfunctioning engine exploding, a structural problem causing a fire on the plane or wreckage hitting the ground.

"The number of heat signatures is crucial," said CNN aviation analyst Miles O'Brien. "If, in fact, only one was detected, that in some respects might steer one away from a missile launch and onto some idea of an explosion onboard the aircraft." 

A top Russian aviation official has said the plane broke apart in midair.

Alexander Smirnov, a Metrojet official, told reporters in Moscow on Monday the airline had ruled out technical problems and human error. Protection systems on the plane would have prevented it from crashing, he said, even if there were major errors in the pilot's control equipment.

The Egyptian military said militants in Sinai have shoulder-fired, anti-aircraft weapons that shoot only as high as 14,000 feet, far short of the more than 30,000 feet at which Flight 9268 was flying when it dropped off radar.

Kremlin spokesman Dimitry Peskov refused to discount terrorism, telling CNN's Matthew Chance on Monday that "only (the) investigation can rule out something."

Metrojet executives also said Monday that it was too early in the investigation to speculate or draw any conclusions. But Smirnov referred to purported footage of the crash posted by militants, saying: "Those images you have seen on the Internet, I think they are fake."