OTTAWA - Toronto's Pearson airport is being dropped from a global review of airport efficiency after a complaint about its embarrassingly low ranking.

The president and CEO of the Greater Toronto Airports Authority demanded the removal of Pearson from the annual survey of more than 150 major airports in a toughly worded letter last August.

"Should you decline this request, I see no other recourse than to pursue all means at our disposal to receive fair treatment,'' Lloyd McCoomb warned the lead researcher at the University of British Columbia.

McCoomb cited a "total lack of academic rigor'' and "unsupported findings'' in the survey, saying the research was "threatening potential harm to our reputation.''

The 2007 edition of the report found that Pearson was among the least efficient airports in the world, and that its cost competitiveness was low. The survey noted that aircraft landing fees at Pearson -- Canada's largest airport -- are the highest in the world.

The survey is published by an international research group of 13 academics, headed by Tae Oum, a business professor at UBC. Detailed results are available for a fee of US$500, to help underwrite research costs, though a free summary is posted on the Internet.

Oum said McCoomb's "intimidating'' letter rattled him and, fearing legal action, he consulted the university's lawyer and others. In the end, the research group agreed to cut Pearson from the efficiency analysis in the 2008 edition of the survey, due in late May.

"I have to protect myself,'' Oum said in an interview.

The 2008 survey, however, will continue to rank Pearson's landing fees and other factual information that is generally available from public sources.

Oum declined to comment on his latest internal findings about Pearson's efficiency, citing McCoomb's letter, but said the airport's ranking has been relatively low for several years.

A spokesman for McCoomb said the president was not threatening legal action but, as a former professor of civil engineering at the University of Toronto, was simply speaking "academic to academic.''

"There's no attempt to shut down research,'' Scott Armstrong said in an interview. "Academic freedom is not an issue.

"What's at issue is we're simply asking that if someone is going to go around making accusations about our company, as any business would be, we're concerned about that, so we want to know where they're coming from.''

McCoomb challenged Oum's methodology and asked for access to the raw data so that a third party, hired by the GTAA, could make an independent assessment, Armstrong said. "That request was not honoured.''

Oum says the research group decided "to keep the (international) data in house for competitive reasons,'' but offered to provide McCoomb all the raw data about Pearson, most of which the GTAA itself supplied last summer.

He acknowledged that the group's methodology -- well-known among economists -- is not the only one applicable, but said even when other analyses of efficiency are used, Pearson's results are similar.

"Basically, your airport needs to improve operating efficiency by benchmarking with more efficient airports,'' Oum told McCoomb in a written exchange last summer.

The Canadian Press obtained copies of relevant correspondence in the dispute.

At least one subscriber to the three-volume survey said both sides need to resolve the impasse.

"This does concern us,'' said Fred Gaspar of the Air Transport Association of Canada, representing commercial airlines.

"Clearly, it is in the interest of every stakeholder in commercial aviation to have access to full and transparent information about the costs of the aviation system.

"Dr. Oum is a highly respected academic international aviation researcher, so it would be our hope and expectation that he and the GTAA would be able to sort out any questions related to methodology.''

Between 100 and 200 copies of the full airport survey are sold each year, mostly to airlines, investment bankers, airports and industry groups. No other airport has ever demanded to be dropped from the study, Oum said.

The 2007 study's findings echo those of internal Transport Canada "scorecards'' for 21 airport authorities across the country, obtained by The Canadian Press.

An analysis of the scorecards by the non-partisan lobby group Transport 2000 found that Pearson ranks poorly on efficiency when measured against comparable airports, such as Calgary and Vancouver.

Critics say an overly ambitious $4.4-billion construction program, along with high rents charged by Transport Canada, have made it difficult for the GTAA to operate efficiently.