COPA Corner: Flight Through Thunderstorms is Asking for Trouble

by Donald Anders Talleur. This article was originally published in the October 2010 issue of COPA Flight under the “Pilot’s Primer” column.

I write this article shortly after Flight 8520, an AIRES Boeing 737, crashed while on approach to San Andres Island, a Colombian resort area. While the investigation of this crash is still ongoingFootnote 1, I feel compelled to focus on one prominent circumstance that could have played a role in bringing this aircraft to the ground prematurely. 

According to all reports, Flight 8520 was flying through a thunderstorm during the approach to landing. While I do not intend to speculate on the particulars of this crash, its occurrence is a reminder that there are inherent dangers in attempting to fly through a thunderstorm, and it is those dangers that I’d like to address this month. 

Thunderstorms contain some of the scariest weather known to man, and the danger of that weather is well known. 

Wind shear, microbursts, hail, lightning and turbulence are the main hazards and exist in thunderstorms to varying degrees depending on the size and strength of the storm. I should point out that size and strength are generally synonymous in that a storm with very high tops is also generally capable of producing the worst weather. 

Although wind shear and microbursts can occur independently of a thunderstorm, as “painted” on the radar, those associated with a thunderstorm frequently produce the most hazardous flight conditions. 

There are a slew of accident cases that list wind shear/probable microburst as contributing to the ensuing loss of control. The typical situation is that an airplane gets into a wind shear situation close to the ground during approach to landing. A sudden shift in headwind component means a loss of indicated airspeed. 

On final approach, the margin between indicated and minimum safe flying speed is small, so any sudden loss of airspeed often signals the need for immediate action on the pilot’s part. Failure to react quickly can result in a stall or even premature ground contact. Typically, wind shear close to the ground does not exceed 20 kt, so it can usually be “powered” out of. That being said, if a report for wind shear exists, extreme caution should be taken when attempting a landing in such conditions. 

If wind shear is encountered during landing or takeoff, the airspeed loss or gain and the altitude of occurrence should be reported to ATC. 

While wind shear is relatively common, a less common type of wind shear event is the microburst. If there can be a worst-case wind shear scenario, I’d have to say that a microburst is it. Years ago, I saw what a microburst could do when one hit a small airport northwest of the Chicago, Ill. area.

The damage was amazing. If it hadn’t been classified as a microburst, I might have suspected a mini-tornado. Tied down airplanes were uprooted, and one was even found upside down on top of a nearby hangar. A nearby barn was flattened. Now picture yourself trying to fly through something that could do all of that! 

Several airliners have tried over the years and failed miserably. An L-1011 crash at Dallas/Fort Worth a bunch of years ago was tragic testimony that a microburst can bring down the largest of aircraft. 

Since then, some pretty smart folks in the U.S. have looked into the microburst phenomenon and made startling findings. They found that microbursts are a whole lot more common than anyone had previously thought. Through the use of sophisticated measuring equipment they mapped out microburst activity at and near major airports across the U.S. and came to the conclusion that microbursts are possible anywhere there is convective activity (i.e. thunderstorms). 

Although many microbursts were of an intensity that a large airplane might make it through, many more were of an intensity greater than what brought down that L-1011. While I won’t go into the gory details of how a microburst works in this article, it’s clear that the name of the game is to avoid microbursts in the first place. The best way to do that is to stay away from thunderstorms. 

Another hazardous feature of thunderstorms is turbulence. Although generally brief, turbulence in a thunderstorm can be quite violent. The combination of updrafts, downdrafts, swirling and shifting patterns of air within a thunderstorm can lead to turbulence that is too difficult for even a jetliner to traverse. 

Case in point, just today there was news of a jetliner on the east coast of the U.S. that diverted for landing after encountering severe turbulence in or near a thunderstorm. This is exactly the type of weather event that should be avoided if possible. 

However, the major difficulty in avoiding turbulence is due to the difficulty of accurately predicting its whereabouts. Luckily, with the advent of Doppler radar, air currents likely to produce turbulent conditions are more easily identifiable. Still, air current activity in a thunderstorm changes frequently, making precise predictions impossible. 

As a result of the somewhat stealthy nature of turbulence, as a general rule, expect it anywhere near or within a thunderstorm. 

One inevitability is where there’s a thunderstorm, there’s lightning. This point is academic since to have thunder there must be a preceding bolt of lightning. Lightning is rarely accused of bringing down airplanes these days (although it has happened and will probably happen in the future) owing to advances in the bonding of aircraft structures to facilitate the better distribution of the charge and subsequent discharge back into the air. At worst, airliners generally suffer nonstructural issues such as nose cone or wing tip damage, but there have been a few suspected cases where a strike led to a fuel tank rupture and tragic results. 

Newer aircraft with composite structures present new problems in that a strike can lead to delamination of material near the strike zone as well as the conventional damage expected at the discharge point(s). Since there is really no way to know how a given aircraft will react to a strike, the best solution is to stay at least 10 mi. clear of thunderstorms. Why so far, you might ask? Simple! Lightning need not stay in the cloud, and if your airplane is a convenient object to attract the strike, then… tag—you’re it! 

One last serious hazard, as if the others weren’t bad enough already, is hail. Imagine your friend throwing ice cubes at you from a distance of 10 ft. It probably won’t kill you, but if he throws them hard enough, expect some small bruises. Now imagine him throwing those cubes at you at 200 kt. Ouch! 

A jetliner flying through hail won’t “feel” much better, and the Internet is full of interesting pictures of damage caused by relatively short encounters with hail. Busted or completely shredded nose cones, busted windshields, leading edge damage that will make you think the airplane flew through a baseball factory; these are serious problems to be sure.

The damage to a small airplane can be equally as bad even though the speed is usually much lower. Slower aircraft will be slower to exit the hail and that means more time for damage.

So how does a pilot avoid hail? Well, for starters, never fly under anything that looks like the anvil of a thunderstorm, and also don’t fly through the vertical thunderstorm cloud. Although hail falls in relatively predictable areas of a storm, a pilot does not generally have the information available during flight to select the right path. Also, although you might fly in the clear air below an anvil, it may be difficult or impossible to spot hail falling prior to running into it.

If I’ve scared you enough to keep you out of thunderstorms then I’d say this article has been a success. These weather phenomena are serious hazards to all aircraft and should be avoided at all costs. Don’t believe that just because someone you know made it through a storm, that it’s possible to do so on a regular basis.

The only way an airplane makes it through a full-blown thunderstorm unscathed is by luck. Don’t get me wrong, luck is good, but if you’re not the type to gamble your entire life savings on a card game, then you might just want to wait out that thunderstorm. The odds of winning the card game are probably better than winning a bout with a thunderstorm.

This month’s Pilot Primer is written by Donald Anders Talleur, an Assistant Chief Flight Instructor at the University of Illinois, Institute of Aviation. He holds a joint appointment with the Professional Pilot Division and Human Factors Division. He has been flying since 1984 and, in addition to flight instructing since 1990, has worked on numerous research contracts for the FAA, Air Force, Navy, NASA and Army. He has authored or co-authored over 200 aviation-related papers and articles and has an M.S. degree in Engineering Psychology, specializing in Aviation Human Factors.

2013 David Charles Abramson Memorial (DCAM) Flight Instructor Safety Award

The recipient of the 2013 DCAM Flight Instructor Safety Award is Chris Walsh of Moncton Flight College (MFC), Moncton, N.B. The award was presented to Mr. Walsh by award co-founder and national administrator Jane Abramson on November 18, 2013, at the Air Transport Association of Canada (ATAC) Annual General Meeting and Tradeshow in Montréal, Que.

Left to right: Jane Abramson, Chris Walsh and Orville Hewitt at the DCAM Award presentation ceremony in Montreal, Que. (Photo: Mike Doiron)
Left to right: Jane Abramson, Chris Walsh and Orville Hewitt at the DCAM Award presentation ceremony in Montreal, Que. (Photo: Mike Doiron)

Chris Walsh made a significant contribution to the development and management of MFC’s approved training organization and the subsequent launch of the multi-crew pilot licence. He has consistently demonstrated high levels of professionalism, commitment and acute understanding of the complexities of operating a flight training unit in a safe and productive environment.

Two deserving nominees were also recognized for their professionalism: Heather Philpott, assistant chief flying instructor at Gander Flight Training, Gander, Nfld., and Deanna Wiebe, assistant professor of aviation at Mount Royal University, Calgary, Alta. Both received courtesy attendance to professional development workshops.

In addition, a new legacy award was created in 2013, which will be awarded on an ad hoc basis to deserving flight training builders. Orville Hewitt, chief flight instructor at Cooking Lake Aviation Academy, Sherwood Park, Alta., was chosen to receive this special honour. Mr. Hewitt has created a significant training and instruction history and was honoured with a special DCAM plaque and an engraved aviator watch.

The annual DCAM Award promotes flight safety by recognizing exceptional flight instructors in Canada and has brought recognition and awareness to the flight instructor community. The deadline for nominations for the 2014 award is September 14, 2014. For details, please visit

Pandemic and Communicable Diseases—Spread Prevention

by the Civil Aviation Contingency Operations Division, National Operations, Civil Aviation, Transport Canada

Have you ever sat on a crowded flight surrounded by individuals who are repeatedly coughing or look feverish? Considering the air inside the aircraft cabin is recycled and that it could potentially be carrying airborne germs from one person to another, you wonder if the government has something in place to prevent diseases from spreading by airplane.

Aircraft air flow
Aircraft air flow


Transport Canada (TC) Civil Aviation Contingency Operations (CACO) focuses on contingency operations and emergency planning. The objectives of the TC Civil Aviation plans are to provide for the coordination and assessment of information related to a pandemic’s impact on the National Civil Air Transportation System (NCATS); monitor the ongoing safety of the NCATS; support an expeditious recovery of the NCATS; outline possible regulatory actions appropriate to the issues arising during an event; address business continuity issues related to the availability of TC personnel; and support other departments in executing their regulatory duties. As part of emergency preparedness, CACO develops and maintains the Plan for Pandemics and Communicable Disease Events under the authority of the Minister of Transport. CACO updates these plans on behalf of the Director General, Civil Aviation (DGCA) and supports the DGCA in the assessment of event-related risks and the implementation of a Civil Aviation response. 

To mitigate the spread of pandemic and communicable disease events by air travel, TC CACO developed plans, memoranda of understanding (MOU) and procedures in accordance with the Emergency Management Act (EMA), the Quarantine Act and associated regulatory requirements. The EMA requires that all Ministers accountable to the Parliament of Canada plan for, prepare for and respond to emergencies related to their area of responsibility. In accordance with the Quarantine Act (2005), the Minister of Health is responsible for establishing quarantine stations and designating quarantine officers and environmental health officers. The Quarantine Act is intended to prevent the introduction and spread of communicable diseases arriving into or departing from Canada. It applies to travellers, conveyances, goods and cargo. Under the Quarantine Act and the Canadian Pandemic Influenza Plan for the Health Sector, the Public Health Agency of Canada (PHAC) is responsible for the promotion and protection of Canadians’ health. To assist the PHAC in its mandate, a MOU between TC Civil Aviation, the PHAC and Health Canada (HC) was established to facilitate coordination and exchange of operational information during a pandemic or communicable disease event.


CACO’s personnel have delegated authority, in accordance with the Aeronautics Act, to maintain a safe, secure, efficient and environmentally responsible air transportation system. If required, CACO can divert an aircraft, restrict airspace, facilitate the exchange of information among stakeholders, and make recommendations to airlines regarding the cancellation of flights to and from international destinations with known contagious disease outbreaks.

In addition, personnel from various agencies, stakeholders (i.e. Canada Border Services Agency, Canadian Air Transport Security Agency and PHAC quarantine stations) and airlines  are trained to identify individuals who appear sick and are able to refer them for secondary screening. In serious instances where an illness is detected in flight, an aircraft may be isolated upon landing, away from the terminal, until quarantine officers are brought aboard to assess the individual(s).


During the H1N1 pandemic in 2009, CACO was involved in interdepartmental working groups with PHAC, HC and international partners such as Mexico and the United States. In cooperation with these partners, the Civil Aviation Contingency Plan for Pandemics and Communicable Disease Events was developed and the Communicable Disease and Public Health Risk Air Traffic Operational Response Concept of Operations (Trilateral CONOPS) was updated. Thus, we endeavour to promote the planning and execution of air traffic-related response efforts in a well-coordinated, mutually supportive, timely and effective manner both domestically and internationally.

In addition, CACO helped disseminate information, such as the Health Alert Notice below, to airlines during H1N1:

Health Alert Notice Human Swine Influenza Public Health Agency of Canada Message for International Travellers Returning to Canada from Mexico. During your time outside Canada, you may have travelled through a human swine influenza - affected area. What is Human Swine Influenza? Swine influenza (sometimes called swine flu) is an influenza virus that usually affects pigs, but which may also make people sick, Human swine influenza is a respiratory illness that causes symptoms similar to those of the seasonal flu (fever, fatigue, lack of apetite, coughing and sore throat). Not all travellers with influenza symptoms will have human swine influenza, however it is important to ensure that if you do experience these symptoms you follow the recommendations described below. if you have a fever and a cough: Notify one of the airline crew immediately if you are on the plan, and notify a Canadian Border Service officer when you go through Customs. If you develop a fever and a cough over the next 7 days: Seek medical attention immediately, Inform a health care provider of your symptoms and your recent travel history. If you are sick, stay home and avoid direct contact with others if possible, unless directed to seek medical care. Protect yourself and others: wash your hands often - for at least 15 seconds - in warm soapy water or use alchohol based hand gel. if you cough or sneeze, cover your mouth and your nose with your arm. Keep common surfaces and items clean and disinfected. Knowledge is yoru best defence. For more up-to-date - Health Alerts and for more information visit: or call 18004548302

By sharing information on communicable disease outbreaks internationally, based on World Health Organization (WHO) pandemic alert phase levels, individual countries are able to prepare for and mitigate associated risks.

The WHO has established phases modelled on the identification and spread of diseases, such as influenza, explained by the PHAC as follows:

WHO Pandemic Phases
Inter Pandemic Phase 1: No new virus subtypes in humans. Animals in Canada or abroad may be infected with a new subtype that is considered low risk for humans.
Phase 2: No new virus subtypes in humans. Animals in Canada or abroad infected with a new subtype that has a substantial risk for humans.
Pandemic Alert Period Phase 3: Human infection(s) with a new virus subtype occurring in Canada or abroad. No or rare instances of human-to-human transmission.
Phase 4: Clusters with limited human-to-human transmission; spread is localized.
Phase 5: Large cluster(s) with human-to-human transmission still localized, suggesting that the virus may be becoming better adapted to humans but may not yet be fully transmissible (substantial pandemic risk).
Pandemic Period Phase 6.0: Increased and sustained transmission in the general population abroad. No cases identified in Canada.
Phase 6.1: Pandemic virus detected in Canada (single cases occurring).
Phase 6.2: Localized or widespread activity occurring in Canada.

In Canada, possible scenarios that would require a plan’s implementation are:

  • TC is alerted to a Phase 4 condition found in a region of Canada or a Phase 5 abroad.
  • TC is alerted to a Phase 6.0 pandemic or communicable disease event in a foreign country serviced by a Canadian air carrier that, for its own reasons, has ceased to service that destination. Canadians are unable to return home.
  • TC is alerted to a Phase 6.2 pandemic or communicable disease event in Canada with widespread activity.

CACO continues to closely monitor the NCATS and, with the aid of stakeholders and international trading partners, aims to keep Canadian skies pandemic free.

Important Enhancements to CAP and RCAP

by Chuck Montgomery, Director, Aeronautical Information Services (AIS), Flight Operations and CNS Operations, NAV CANADA

NAV CANADA will be modernizing the format of the Canada Air Pilot (CAP) and Restricted Canada Air Pilot (RCAP) publications, starting with the first publication cycle in 2014.

Several improvements will be made, including the introduction of constant descent angle depictions, restructured communication blocks and other human factors related changes.

The types of charts affected by these changes include:

  • Instrument Approach Procedures;
  • Helicopter Procedures;
  • Arrival (STAR); and
  • Departure (SID).

Constant descent angle depictions

A key change, the depiction of constant descent angles on non-precision approach charts, will make it easier for pilots to understand and fly a constant flight path on final approach to the runway. This contributes to pilot situational awareness and helps reduce workload when completing stabilized descents.

Constant descent angle depictions reduce the probability of infringement on required obstacle clearance during the final approach segment, reduce noise levels and improve fuel efficiency by minimizing the level flight time at higher power or thrust settings.

The Transportation Safety Board of Canada (TSB), as a result of investigations into certain controlled flight into terrain accidents, has noted that during step-down approaches, aircraft are flown at minimum altitudes for a longer time, exposing people to increased risks of approach and landing accidents. The TSB has identified the benefits of depicting constant descent angles rather than the line joining the obstacle clearance altitudes.

Understanding what is changing

NAV CANADA, in partnership with the Canadian Council for Aviation and Aerospace, developed orientation information to help customers understand upcoming changes. The training package has been delivered in workshops throughout Canada over the past year.

If you are interested in reviewing presentation material explaining the changes in detail, this information can be accessed on the NAV CANADA Web site here.

Implementation of changes

Given the need to convert a large volume of charts to the new format, implementation of the changes referenced will occur over multiple publication cycles as follows.

06-FEB-14                  CAP Volumes 1 and 2

03-APR-14                  CAP Volumes 3 and 7

29-MAY-14                CAP Volumes 5 and 6

24-JUL-14                   CAP Volume 4 and RCAP

Further information on the implementation of these changes and the associated timelines can be found in AIC 33/13.




Footnote 1

The final occurrence report into the AIRES Flight 8520 accident has been released by Colombian authorities since the original publication of this article. The probable cause of the accident was: “Execution of the flight below the angle of approach, due to a misjudgment of the crew, believing to be much higher, leading the aircraft to fly a typical trajectory of a ‘black hole’ illusion, which was experienced during the night-time approach to a runway with low contrast surrounded in bright focused lights, aggravated by bad weather of heavy rain.” (from the Aviation Safety Network’s Web page on Flight 8520)

Return to footnote 1 referrer

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