Flight Training - October 2019 - 24

PREFLIGHT ACCIDENT REPORT

BY DAN NAMOWITZ

TOO MANY WAKES
DID CONFUSION, FATIGUE CONTRIBUTE TO A FATAL CRASH?
IT WAS THE FOURTH LEG OF FLYING FOR

INSIDE THE AIM

WEIGHT A MINUTE
Understanding wake
turbulence
Wake turbulence is
defined in the Pilot/
Controller Glossary as "a
phenomenon that occurs
when an aircraft develops lift and forms
a pair of counterrotating vortices." Earlier
aircraft-separation standards were based solely
on aircraft weight, but
NextGen modernization
of the air traffic system
includes a "wake recat"
component-recategorizing aircraft for
purposes of wake turbulence separation, and in
some cases reducing the
required separation.

Refresh your
knowledge of wake
turbulence in Aeronautical Information
Manual 7-3.

the Beechcraft Bonanza A36's pilot on a
day in which he had covered nearly 1,000
miles, round trip. Now, with the journey's
end near, air traffic control informed him
to expect Runway 25 for landing-and a
bit of a delay.
The pilot replied that he could accept
Runway 16L instead. The controller
instructed him to continue for landing-
but did not specify for which runway. Nor
did the pilot ask for clarification.
It's easy to see how this scenario could
deteriorate. A few more complications
turned a dicey situation at Nevada's Reno/
Tahoe International Airport on August 30,
2016, into something much worse.
The tower again radioed with instructions to continue for Runway 25, but "the
pilot reported that the airplane was on
a downwind leg for landing on Runway
16L," according to the National Transportation Safety Board, which noted that
the controller "acknowledged and, rather
than correcting the pilot, instructed him
to continue inbound for 16L."
To the fatigue and confusion, a new
risk element was added: "At the time,
Runway 16R was being used for landing
by two Boeing 757 airplanes in sequence,
separated from each other by about 7
miles," the NTSB report said.
Light aircraft should always give
airliners a wide berth in airport traffic
patterns, but as you may recall from your
ground school study of wake turbulence,
the Boeing 757 has a reputation as a
wake-maker. It is therefore afforded more
separation than comparable-size aircraft.
The controller advised the Bonanza
pilot-a veteran aviator who was the
co-owner and chief instructor of a local
flight school-that a 757 was on a 9-mile
final for Runway 16R. ATC cautioned him
about wake turbulence and cleared the
Bonanza to land. The two parallel runways'
centerlines were 700 feet apart.
The Bonanza pilot said he had "the airliner" in sight-but which one had he seen?

24  FLIGHT TRAINING OCTOBER 2019

According to the NTSB, the jet on final was 4.5 miles ahead,
and lower than the Bonanza. The other 757 was 5 miles away
"at its 2-to-3-o'clock position. Given that the pilot's attention
was likely focused toward the runway during this portion of the
approach, it is likely that he misidentified the ATC-reported traffic as the 757 on short final, which landed soon after and likely
resulted in the pilot relaxing his vigilance in looking for traffic."
Although the tower now reported winds from 250 degrees at
17 knots, gusting to 20 knots, the Bonanza continued for Runway
16L even though "these wind conditions met or exceeded the
airplane's maximum demonstrated crosswind capability for
a landing on 16L, and the airplane was still well-positioned to
revert to an approach to Runway 25," the report continued.
Just after the Bonanza turned base, the second Boeing
passed a mile ahead and slightly below it; it was unknown if the
Bonanza pilot saw it or "was cognizant of the potential for a
wake vortex encounter and the flight path alterations necessary
to avoid such an encounter."
Witnesses said the flight path appeared normal, but "when
the airplane was on about a 1/2-mile final approach, at an altitude of less than 200 feet above ground level, it suddenly rolled
and descended to the ground." The 73-year-old, 11,300-hour
pilot and a passenger died when the aircraft crashed in a Sparks,
Nevada, trailer park, requiring the evacuation of some residents,
according to news reports.
The NTSB assigned probable causes, including the pilot's
selection of a landing runway "susceptible to high crosswinds
and the translation of wake turbulence across its approach
path," and "the controller's and pilot's failure to ensure
separation from the B757 and its wake, which resulted in a
low-altitude encounter with wake vortices that the pilot was
unable to recover from."
The report discussed at length the communications aspects
of the accident sequence, noting that "had either the controller
or the pilot specified the location of the traffic once the pilot
reported it in sight, that information would have significantly
improved the likelihood of detecting the pilot's identification
error." It added that although the controller had "relinquished"
responsibility for traffic separation, this had been done without
explicitly assigning it to the pilot.
The pilot's experience suggested little reason to doubt that
he would have been aware of the crosswind condition he faced,
or of wake turbulence "behaviors and hazards."
As for the pilot's long day of flying, investigators could not
assess its effects on his alertness, decision making, misidentification of the conflicting traffic, or what the NTSB described as
"vague communications" with air traffic control.
dan.namowitz@aopa.org
Flight Training - October 2019

Table of Contents for the Digital Edition of Flight Training - October 2019
