Before Air Collision, a Warning

Moments before two planes collided over Denver, air traffic controllers told one pilot that the other aircraft was directly ahead of him, but they did not warn either plane to take evasive action, federal investigators said Monday.

All five people aboard the twin-engine Piper Comanche II and the single-engine Cessna 172 died in the Friday crash. Although the Cessna plunged into a house and the Piper narrowly missed another home, no one on the ground was injured.

The dead were identified Monday as Cessna pilot Jonathan Ladd, 20; his passengers, Curtis Paul Maxey, 22, of Littleton, Colo., and Isaac Lewis Morrow, 22, of Granby, Colo.; Piper pilot Leo Larson, 57, of Northglen, Colo.; and his passenger, Fred White, 51, of Westminster, Colo.

The National Transportation Safety Board said Monday that both pilots had been granted an optional service known as “flight following.” Under this service, air traffic controllers track the planes on radar. Although they are not specifically required to, the controllers frequently advise the pilots of traffic near them and warn them to change course if another plane seems dangerously close.

About 5 p.m. Friday, the Cessna took off from Centennial Airport, southeast of downtown Denver, for a flight to Cheyenne, Wyo. Ten minutes later, the Piper took off from Jefferson County Airport north of the city, en route to Centennial Airport.

At 5:17 p.m., Larson told a controller that he was at an altitude of 7,800 feet. About 90 seconds later, the same controller granted Ladd’s request to climb from 7,300 feet to 8,500 feet.

The controller asked Larson for his location. Larson replied that he had dropped to 7,600 feet.

According to the NTSB, the controller then warned Larson that the Cessna was one mile dead ahead at an altitude of 7,700 feet. Although the controllers often advise pilots to turn away under such circumstances, the controller did not warn either pilot to make an evasive maneuver.

“The collision occurred shortly thereafter,” the NTSB said.

Investigators said the collision occurred about 20 minutes after sunset amid broken clouds.