Third Trans States Landing Accident in Ottawa Raises Questions About Runway Design

 - October 4, 2011, 8:40 PM

Authorities in Canada are investigating a September 4 runway excursion at Ottawa International Airport involving a Trans States Airlines Embraer ERJ 145–the third such incident involving an ERJ 145 operated by the St. Louis-based regional airline at the same airfield.

Flying as United Express Flight 3363 from Chicago, the 50-seat regional jet carried 44 passengers and three crewmembers, none of whom suffered injuries, when at about 3:30 pm it skidded off the side of a wet, 10,000-foot-long Runway 14-32. A recovery crew removed the airplane from the site on Monday but at press time investigators had not commented on possible causes.

The most recent runway incident came some 15 months after another ERJ 145 operated as United Express by Trans States from Washington Dulles International Airport overran Ottawa’s 8,000-foot Runway 07-25 by some 500 feet, again in wet weather. Both pilots and one of the 33 passengers suffered minor injuries in that accident, but the airplane sustained severe damage after its nose gear collapsed in the soft ground. The Transportation Safety Board of Canada has not concluded its investigation into that June 16, 2010 accident.

The Board did cite several “operational and human factors” in a report on a 2004 overrun by another Trans States ERJ 145 that originated in Pittsburgh. Operating as US Airways Express, again in wet conditions, the aircraft approached Runway 07-25 “high, fast and not stabilized,” resulting in the aircraft touching the ground almost halfway down the 8,000-foot runway. However, the report also said that the smooth landing most likely contributed to hydroplaning and that the anti-skid system most likely prevented the brake pressures from rising to normal values until 16 to 19 seconds after so-called weight on wheels, resulting in little or no braking action immediately after landing.Finally, the Board faulted the pilots for being slow to recognize and react to the lack of normal deceleration, thereby delaying the transfer of control to the captain, which might have contributed to the overrun.

Flight Safety Foundation director of technical services Jim Burin told AIN that the lack of grooves in Ottawa’s runways or the fact that the airplanes in question do not have thrust reversers certainly might have contributed to the most recent accident, but he also said factors such as crosswinds likely came into play. He also hesitated to draw any parallels among the three Trans States accidents other than to guess that the Ottawa airport sees a lot of ERJ 145 traffic.

“On a dry runway, thrust reversers are nice to have, but on a contaminated runway they become very, very important,” he said. Burin added that runway grooves can reduce the risk of contamination, but that the existence of a smooth runway rarely accounts for the only factor in an excursion. “You can say, ‘Well, if the runway were grooved you wouldn’t have the accident.’ That’s not usually the case,” stressed Burin. “If you have other conditions–land long, land fast, a crosswind–and, by the way, there’s standing water on the runway, now you’ve added enough factors together [to cause] an accident, whereas if one of those were missing, you might not have.”     

In fact, most of Canada’s runways lack grooves, presumably due to the damage ice and snow can inflict on concrete during repeated freezing and thawing, surmised Burin. Asked for official comment on the reason, Transport Canada sent AIN an e-mail that explained the alternative methods the country’s airports use to aid stopping authority. “In Canada, runway surface drainage is handled by the slanting of runway slopes and the use of surface texture to enhance friction characteristics,” said Transport Canada. “Airports are required to have [an] on-going program for the removal of surface rubber deposits for the maintenance of runway friction characteristics. In Canada, runway grooving has been used only to address site specific issues such as standing water or to promote drainage on runways with low or problematic transverse slopes.”

Comments

Ian Kjargaard's picture

Ice and snow does not damage a grooved runway. If it was, airports such as Sitka, Alaska would not have it's runway grooved if that were the case. The FAA Advisory Circular (51) suppports grooving: "grooves cut into the pavement will trap anti-icing/deicing chemicals, thus reduceing loss and prolong their actions. It has also shown grooves delay the formation of ice." Transport Canada's Publication TP 14842E states that ice formation in no way affects the pavement of a grooved runway. The findings also staes that"grooved or PFC runways reduced the risks of an accident on a wet runway by approx. 75 %.

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