“The flight recorder, whose tapes are being deciphered, did not register any pressure on crew members,” said the official, in an interview with the Interfax news service on Thursday.

The official said that the pilot was aware “well in advance” that he was headed to an airfield without a modern aerial navigation system. One possibility, he said, was that the pilot was not aware that the plane, a TU-154, loses altitude faster than usual when it is descending at more than 20 feet per second.

Newsletter Sign Up Continue reading the main story Please verify you're not a robot by clicking the box. Invalid email address. Please re-enter. You must select a newsletter to subscribe to. Sign Up You will receive emails containing news content , updates and promotions from The New York Times. You may opt-out at any time. You agree to receive occasional updates and special offers for The New York Times's products and services. Thank you for subscribing. An error has occurred. Please try again later. View all New York Times newsletters.

Anatoly Muravyov, an air traffic controller who was on duty that morning, told the newspaper Komsomolskaya Pravda that the crew had begun a landing without permission when air traffic controllers warned them about the weather and recommended that they land at another airport.

When the crew did not change course, he said, “all we could do was to continue to guide the plane and watch.” He said he attributed the crash to “weather conditions, maybe crew error, uncontrolled loss of altitude and the pilot’s desire to land the plane at any costs.”

Tatyana Anodina, the head of the Interstate Aviation Committee, which oversees aviation in the former Soviet Union, denied reports that the pilot made three or four attempts to land, and said he made only one. She urged the public not to trust unofficial sources on the cause of the crash.

In Poland, meanwhile, some members of the late president’s Law and Justice Party remained suspicious of the Russian inquiry. Jolanta Szczypinska, one of the party’s senior members, called for a nonpartisan, international commission to investigate.

Ms. Szczypinska, who gave up her seat on the flight just hours before it took off, said she had been informed by Polish journalists at the crash site that Russian authorities demanded that witnesses who had been waiting to greet the dignitaries hand over their cameras and cellphones.

“I have flown many times on that plane and I knew the pilots, and I am convinced that it wasn’t a pilot’s mistake that led to this tragedy,” she said in an interview on Thursday. “It is disturbing the way the Russian side has been communicating, issuing statements, and how they had their version of events from the beginning. It is very strange, and we expect answers.”