PIPER PA-28R-200 near Lake Michigan, WI — 2013-07-27

Probable cause

An encounter with wake turbulence, which resulted in the pilot’s loss of control of the airplane and its subsequent in-flight breakup. Contributing to the accident was the approach controller’s failure to issue a wake turbulence advisory to the pilot.

Contributing factors

Contributing to the accident was the approach controller's failure to issue a wake turbulence advisory to the pilot.

NTSB narrative

The pilot was receiving flight-following services from an approach controller, who gave the pilot vectors to fly east over Lake Michigan and then north to avoid conflicting traffic. On the northerly heading, the accident pilot flew 1.4 miles behind the other airplane. When the accident pilot had the traffic in sight, the approach controller allowed him to pass behind the other airplane and then turn northbound as requested. Shortly thereafter, the approach controller lost radar contact with the pilot. Search and rescue operations were conducted, and the airplane was located in the lake. According to recorded radar data, the accident airplane's flightpath crossed the other airplane's flightpath at 1,800 feet mean sea level (msl) about 39 seconds after the other airplane passed the same location at the same altitude. Because the approach controller's plan explicitly had the accident pilot pass behind the other airplane and the other airplane was descending from above the accident airplane, it is likely that the accident airplane encountered wake turbulence. Primary radar returns detected by airport surveillance radar were consistent with the in-flight breakup of the airplane. The approach controller did not issue a wake turbulence advisory to the pilot. Although wake turbulence is primarily the pilot's responsibility, the Federal Aviation Administration Air Traffic Control Handbook does require controllers to provide pilots with a wake turbulence advisory if, in the controller's opinion, wake turbulence may adversely affect their aircraft. In this case, the approach controller should have been cognizant of the potential hazard and issued a wake turbulence advisory to the pilot.

Analysis

Primary failure mode

Controlled flight into terrain

First missed decision gate

Pilot could have avoided wake turbulence by altering flight path earlier.

NTSB coding

• Aircraft wake turb encounter · Enroute-cruise

Evidence available

• ADS-B / radar
• 8 docket documents

Docket documents8

• ATC 3 - ATC Specialist Reportatc
• ATC 3 - FAA Accident Packageatc
• ATC 3 - MKE Radar Dataatc
• Evidence Control Formform
• Release of Aircraft Wreckage, NTSB Form 6120.15form
• Statement of Party Representatives to NTSB Investigationinterview
• Toxicological Report - Passengerreport
• Toxicological Report - Pilotreport

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