NTSB Safety Alert SA-035 - Preventing Obstacle Collision Accidents

Preventing Obstacle Collision Accidents in

Agricultural Aviation

Both unseen and known obstacles present unique hazards .

The proble m

 Accident s involving collisions with obstacles are among the most common types

of agricultural aircraft accidents. During 2013, 1 6 accidents involved aircraft that

collided with poles, wires, guy wires, meteorological evaluation towers ( MET ), or

trees while conducting agricultural -related activities .

 Some collision s involved obstacles that the pilots did not see (even during survey

flights) but others involved obstacles that were known to the pilot and/or had

characteristics that would make them visibl y conspicuous .

Related accidents

 While applying herbicide to a field, a pilot of a PZL Mielec M -18A airplane was

killed after his airplane struck two guy wires of a radio tower. The pilot was

previously aware of the marked radio tower an d had worked the ta rget field at

least 15 times during the previous season . (CEN13LA163 )

 A pilot of a Bell 206B lost control of the helicopter after flying through power lines.

The pilot had circled the target field three times to look for obstacles before

beginning the spray passes but did not see the power lines. (ERA13LA236 )

 At the end of a spray pass in a small field with multiple obstacles, a

Piper PA-36-300 airplane struck a tree on the edge of the field . The pilot , who

was fatigued at the time of the accident, reported that he regretted his decision to

accept a high level of risk to spray the small, tightly confined field .

(CEN13LA464 )

 An Air Tractor AT -802A airplane crashed after striking power lines at the end of a

field. Although the pilot had “scouted” a previous field he sprayed, he had not

circled the field where the accident occurred . Also , the pilot was flying toward the

sun, which likely affected his ability to see the power lines. (CEN13LA424 )

SA-035 May 2014 , revised D ecember 2015 What can pilots and operators do?

 Maintain a quick -reference document (paper or elect ronic) at the operations base

that contain s field maps, charts, photographs, and details of all known obstacles.

Frequently review current aeronautical charts for information about obstacles.

 Before you leave the ground, s pend time becoming familiar with all available

information about the target field and p rogram ming navigation equipment . Such

preflight action can help reduce the potential for confusion or distraction in flight.

 Conduct aerial surveys of the target field but do not rely solely on an aerial

survey to identify potential obstacles .

 Conduct regular ground surveys of fields . Some t owers can be erected in hours ,

and obstacles can change s ince you last worked that field.

 When possible, use ground crews. They may be in a better position to see

certain obstacles and help you ensure that your aircraft remains clear of them .

 Watch for shadows and irregularities in growth patterns to help identify obstacles .

 Speak with farmers and land owners to raise awareness about obstacle hazards .

 Use GPS and other technology to maintain awareness of obstacle locations .

 Be aware that workload , fatigue, sun glare, and distractions in the cockpit can

adversely affect your ability to see, avoid , or remember obstacles .

 Understand the performance limitations and requirements for your aircraft,

particularly when operating with heavier loads and at higher density altitudes .

 The National Agricultural Aviation Association’s Professional Aerial Applicators’

Support System reminds pilots that, when ferrying an aircraft or transitioning

between sites , flying above 500 feet reduces obstacle collision risks:

“Ferry Above Five and Stay Alive ”

Interested in more information?

The Federal Aviation Administration’s (FAA) Advisory Circular (AC) 137 -1A, “Certification

Process for Agricultural Operato rs,” provides some basic tips about obstacle avoidance . The

AC is accessible from the FAA’s website at www.faa.gov .

The FAA “Flying in the Wire Environment ” Safety Alert for Operators (SAFO) 10015

provides information and a link to a video on wire -strike avoidance awareness.

This NTSB safety alert and others , including “Meteorological Evaluation Towers ” (which

provides more information about MET hazards ), can be accessed from the NTSB’s Safety

Alerts web page . The reports for the accidents referenced in this safety alert are accessible

by accident number from the NTSB’s Aviation Accident Database & Synopses web page .