From what I can tell, the story isn’t hinting at a terrorism angle but rather dangerously-relaxed safety and security standards. Anyone who’s traveled on a commercial aircraft in the past few years knows there are two rules to which airlines strictly adhere: No passengers enter the cockpit during the flight, and there’s no use of cell phones while in the air.

MOSCOW – At least two passengers visited the cockpit of Polish President Lech Kaczynski’s plane before it crashed last month, and others may have chatted on cell phones, possibly affecting navigation as the crew battled heavy fog over challenging terrain.

Those were among the details revealed Wednesday by Russian and Polish officials investigating the April 10 crash that killed Kaczynski, his wife and 94 others outside the western Russian city of Smolensk. The preliminary report drew no conclusions about what caused the crash.

Another potential cause of the crash? The terrain surrounding Smolensk airport, where the aircraft was supposed to land.

Alexei Morozov, head of the technical commission of Russia’s Interstate Aviation Committee, told reporters that among the questions that need further investigation is whether the rolling terrain around the Smolensk military airport distorted instrument readings.

The plane went down in a ravine 15 meters (50 feet) below the level of the runway, just a kilometer away.

“The presence of this ravine can have a natural influence on the readings of the radio altimeter,” Morozov said. “This is one of the subjects the technical commission is working on.”

But here’s the most important part:

The most tantalizing detail was that two voices not belonging to crew members showed up on the cockpit flight recorders. Officials said it was not clear to whom one of the voices belonged, declined to identify the other person and didn’t report what either person said.

The information could feed speculation in Poland that Kaczynski or someone in his entourage pressured the crew to land despite visibility that had shrunk to about 200 meters (660 feet). The plane was carrying senior political figures to a memorial ceremony for thousands of Polish officers who were killed by Soviet secret police in 1940.

The unidentified voices are heard just 16 minutes before the crash. Continuing:

Morozov said the Polish air force crew piloting the plane had been assembled only a few days before the flight and that they had not received regular training that could have helped them cope with unusual conditions.

About five seconds before the plane hit a tree in the ravine, the captain switched off the autopilot and started to bank around for a second landing attempt, Morozov said. An automated voice warned “pull up” about 18 seconds before the crash, and before that the crew twice heard the phrase “terrain ahead,” Morozov said.

The pilot appeared to have ignored advice to land elsewhere. About 11 minutes before the crash the crew of a Russian plane informed the Polish crew that it had made two attempts to land before changing course for another airport. Seven minutes later the crew of a Polish Defense Ministry plane that had landed in Smolensk 90 minutes earlier informed the presidential plane that visibility had deteriorated.

Lax security and safety procedures, ignored warnings of low visibility, difficult terrain, insufficient training…perfect storm.