Close call involving F-15, commercial
jet prompts review of flight procedures
By Ron Jensen, U.K.
bureau
RAF LAKENHEATH, England — A series of events — none of them critical on its
own — caused a U.S. F-15 fighter jet to cross within 400 feet of the nose of a
commercial airliner carrying 234 passengers over central England last November, a report
of the near-miss has concluded.
In the wake of the report by the U.K. Air Accidents Investigation Branch, pilots with
the 48th Fighter Wing at RAF Lakenheath, England, have been directed to fly closer
together while crossing in formation through controlled air space in the United Kingdom.
The wing, however, is not comfortable with that directive and is seeking an alternative
solution amenable to the British government and the U.S. Air Force.
"It’s an interim solution, at best," Major J.J. Isherwood, assistant
director of operations for the 48th Operations Support Squadron, said of the directive
that requires aircraft fly within one nautical mile of each other and within 100 feet of
the same altitude.
The report is not the final word on the matter. The AAIB works much like the National
Transportation Safety Board in the United States and presents its version of events.
The Civilian Aviation Authority, which is much like the Federal Aviation Administration
in the United States, will release a report next month.
The "near disaster" occurred about 10:20 a.m., Nov. 22, when the crew on the
flight deck of a Boeing 757 flying from Birmingham, England, to Cyprus watched a two-seat
F-15E cross less than 400 feet in front of them.
The aircraft were so close that the crew of the 757 heard the noise and felt turbulence
from the wake of the fighter jet that was the second aircraft in a two-aircraft formation.
The Boeing’s crew had been alerted to the first F-15, which was flying at a higher
altitude, but was surprised to see the second one. The crew reported the incident and
continued on to Cyprus. No passengers or cabin crewmembers knew of the close call.
The two crewmembers of the F-15E were unaware of their near-miss until later.
The AAIB report finds no single reason for the near-miss, but attributes the
frightening incident to a series of events, some of which prevented air traffic
controllers from knowing two F-15s were in the sky.
Isherwood said none of the events are uncommon and at least one of them probably
happens every day in the busy world of flying.
"It was just a combination of things," he said. "We’ve been flying
here for years, utilizing the same procedures."
The F-15s were about two miles apart, flying through clouds on their way to a training
area in Wales, a flight planned as training for the pilot of the second aircraft. Only the
lead aircraft was transmitting a Secondary Surveillance Radar code — known as
"squawk" — which is a standard procedure. That signal provides ground
controllers with the aircraft’s identity and altitude.
The lead pilot requested permission for him and his wingman to climb to a higher
altitude. Permission was given, but the two flyers in the second aircraft did not hear
this message.
They noticed on radar the altitude change of the lead aircraft. About this time, the
pilot became vaguely aware of a "shadow" off to his right. The
"shadow" was the Boeing 757.
The report concludes that the second F-15 was a surprise because of several factors:
- The radar signal of the lead aircraft partially obscured the radar image of the second
aircraft.
- Because of call-sign procedures used by the Air Force, a formation of aircraft may has a
single call sign, in this case Bolar 31, which does not tell air traffic control if there
is one aircraft or several operating under that call sign.
- The missed radio message in the second aircraft directing them to climb 1,000 feet was
another factor. There is no requirement for that aircraft to acknowledge receipt of the
message, so no one was aware the message had not been heard.
The report is clear that no one factor caused the incident.
And so far, the only change for pilots is the requirement to fly in closer formation.
The U.S. Air Force considers a separation of one nautical mile — about 6,076 feet
— to be adequate in clear skies, but too close when clouds hamper visibility.
"It may not be safe to close up within one mile of a person [while in
clouds]," Isherwood said.
The wing is now working on a guideline to present to aviation officials in the United
Kingdom that it hopes will meet the safety requirements of all concerned.
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