Over the past few years, we've seen corporate reporting firmly enter the mainstream, with companies in sectors as far-flung as energy and retail to technology and construction offering their stakeholders regular progress reports on their environmental, social and financial performance.

The airline industry is no exception, and the number of reports bring published by airline companies has taken flight. The quality, however, is lacking, and the metrics that individual firms track are all over the map, making apples-to-apples comparisons difficult, according to a new report from PricewaterhouseCoopers (PwC).

The Big Four accounting firm took stock of the corporate reporting practices of 46 global airlines in the report, "Building trust in the air: Is airline corporate sustainability reporting taking off?"

The short answer: sort of. Sixty-five percent of airlines in the study filed reports in 2010, a 15 percent increase over 2009. But the average score for quality was just 38 percent (out of 100 percent), in the category PwC has labeled, "Reporting has significant room for improvement."

The reporting quality of seven airlines was deemed "good." They included Air France KLM, Delta, Iberia, LAN Airlines, Lufthansa, Southwest Airlines and UPS.

No airline achieved an "excellent" score.

PwC called for the industry to develop sector-specific reporting guidelines to provide continuity between reports. The firm found some airlines reporting total carbon dioxide (CO2) emissions, while others didn't. A significant minority also didn't report fuel efficiency, and most failed to disclose nitrous oxide emissions.

While the report is obviously tailored for the airline industry, it does offer insight, advice and PwC's predictions of where corporate reporting is heading, all of which would be valuable for any company that reports on its sustainability performance.

"Great sustainability reports will use case studies and qualitative data to help bring the facts and figures to life, but they’ll avoid overly-flowery sales talk," the report said. "Most of all, they’ll help support airlines in making their businesses more sustainable. That’s good news for everyone, from investors to regulators. And the next generation of travelers will appreciate it too."

Airplane image via Shutterstock.