YOKOSUKA NAVAL BASE, Japan — An interfering signal jammed up communications between Haneda Airport pilots and air traffic control Tuesday morning for the third time this month.

It originated off the coast of Yokosuka, according to Japanese ministry officials.

But unlike the Oct. 17 incident, in which 195 planes were grounded and some flights were delayed more than an hour, Haneda’s operations weren’t affected by Tuesday morning’s 40-minute disruption.

The five airplanes that were using the jammed frequency switched channels and were able to communicate with the control tower, said Civil Aviation ministry official Hirotaka Ooguchi.

“The ministry requested the Ministry of Internal Affairs and Communications to investigate and we were told that the interference came from the direction of Yokosuka,” said Ooguchi. “The interference stopped at 11:01 and the source of interference was not identified.”

However, the signal does not appear to have come from either the Defense Agency or U.S. Forces Japan.

“We received responses that both did not use radio waves that would interfere,” Ooguchi said.

This differs from the Oct. 17 event, which Command Naval Forces Japan is “aggressively” investigating to determine whether Navy transmissions interrupted airport business.

“We have no definitive evidence yet that it was us,” said CNFJ spokesman Cmdr. John Wallach. “We’re not convinced it was but we’re going to find out. We’re looking at the entire picture.”

CNFJ is reviewing all electronic emissions that occurred during the three-hour disruption, Wallach said. He didn’t know when a finding would be released, he added.

Pinpointing the cause of Tuesday’s disturbance will be hard as it was a high frequency commonly used by many facilities, Ooguchi said. However, he said, the ministry seeks to prevent similar incidents in the future. Last week, it gave the Defense Agency and USFJ a list of frequencies the ministry uses, asking them to avoid disrupting those frequencies, Ooguchi said.