AIN Blog: To Groove or Not To Groove?

 - September 19, 2011, 12:19 PM
A Trans States Airlines Embraer ERJ 145 skidded off Ottawa’s 10,000-foot Runw
A Trans States Airlines Embraer ERJ 145 skidded off Ottawa’s 10,000-foot Runway 14-32 on September 4. (Photo: Peter Tsagaris)

When a Trans States Airlines Embraer ERJ 145 skidded off the runway in Ottawa on September 4 in wet weather, resulting in no injuries, the relatively minor accident at first generated the modest press coverage it deserved. But something seemed familiar about this runway excursion. In fact, not much more than a year ago another Trans States ERJ 145 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, after the airplane’s nose gear collapsed in the soft ground.

A little digging uncovered a 2004 accident involving yet another Trans States ERJ 145 in Ottawa. Although the Transportation Safety Board of Canada cited “operational and human factors” in its final report–the aircraft approached “high, fast and not stabilized,” before touching down almost halfway down the runway–it also noted that the smooth landing most likely contributed to hydroplaning.

Of course, hydroplaning happens when a vehicle’s tires lose contact with the ground. In the U.S., the FAA requires airports that handle turbojet aircraft to cut grooves in their runways to mitigate the incidence of hydroplaning. No such regulation exists in Canada, and, predictably, almost none of the runways there have grooves.

That’s not to say that if Ottawa’s runways had grooves, the accidents wouldn’t have happened. In fact, a number of factors could have come into play, including the fact that ERJ 145s do not come equipped with thrust reversers. According to Flight Safety Foundation director of technical services Jim Burin, 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.”

Still, that doesn’t explain why Canada doesn’t at least attempt to mitigate one of those potential factors with a requirement for runway grooves. While one might suspect that the frigid winters might play a factor–thawing and freezing of water, ice and snow within runway grooves can, in fact, damage concrete and snow removal equipment can certainly present wear issues, according Chris Oswald, v-p of safety and technical operations for Airports Council International-North America. However, according to Oswald, the reasons lie more with government policy–or lack thereof–than any natural phenomenon.

In fact, he said, the Canadian system simply doesn’t provide for the robust federal participation in infrastructure support U.S. airports have enjoyed through the Airport Improvement Program, for example.

“What [the] FAA has done with its federal requirement is they’re able to back that with some level of federal participation…actually a rather high level when it comes to a lot of safety programs,” he explained. “In Canada, it’s a harder nut to crack, especially when it comes to what can be viewed as, I guess, equivocal safety improvements. And there’s been some debate regarding runway safety areas. Grooving kind of falls into that same onus. When you get new requirements that might be introduced in Canada, I think there’s a bit of a higher bar and a bit of a need for a stronger safety case or sort of an unequivocal safety case to be made.”

Ironically, the largely privatized system in Canada doesn’t seem to provide for a clear and easy path for federal funding for airport safety projects, according to Oswald. Conversely, in the U.S., where the culture tends to view any form of collectivism with suspicion, a more centralized system seems to have at least made paying for runway projects a more straightforward exercise.

Asked for a reason behind the fact that Canadian runways generally lack grooves, Transport Canada first sent me 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.”

Of course, that didn’t answer the question. Later, a spokesperson referred me to each individual airport for an explanation. That seemed to confirm Oswald’s point. In fact, I didn’t see much need for further investigation.