WASHINGTON (AP) — Government and aviation industry officials from dozens of countries are meeting in Montreal this week to try to find consensus on how to keep from losing airliners like the one that vanished without a trace in Asia and another shot down in Eastern Europe.

It is only the second high-level safety conference in the 70-year history of the International Civil Aviation Organization, a U.N. agency, but last year was calamitous. A Malaysia Airlines flight disappeared in March and has not been found. In July, another Malaysia Airlines flight was down shot down while flying over an area of Ukraine where ethnic Russian rebels are trying to secede.

There is broad agreement that the agency should build a database where governments can send intelligence or warnings about risks to aircraft flying over conflict zones. Historically, though, nations other than the United States rarely have posted public warnings about such risks in other countries. Few have global intelligence networks, and it has been considered almost impolite for one country to issue a warning about another. Instead, the practice has been for each country to issue warnings only about its own airspace.

But that is changing.

ICAO, the U.N. agency, sent an urgent warning to members on Jan. 14 that airlines flying over Libya risk being shot down. On Jan. 22, the European Aviation Safety Agency distributed a French warning that flights over Pakistan might be subject to “terrorist attacks.”

Ukraine had warned airlines flying over its territory to remain above 32,000 feet. The Malaysia plane, however, was flying at about 33,000 feet from the Netherlands to Kuala Lumpur, the Malaysian capital, when it was fired upon.

A majority of the 298 people aboard were Dutch citizens. The Netherlands wants airlines to tell passengers before takeoff whether a plane’s flight path will cross a conflict zone. Airlines and other nations say that goes too far.

While sympathetic to the Dutch concerns, “we’re also confident that an ICAO centralized database represents a reasonable balance,” said Kenneth Quinn, former general counsel at the Federal Aviation Administration.

There also are disagreements about whether database information should be screened before being made public, and how to handle conflicting or inaccurate information. Besides official intelligence, the database is expected to include media reports and other unofficial information.

The U.S. does not believe the U.N. agency is capable of evaluating the information and wants sources of reports be identified so users can decide how much weight they want to give them, said a U.S. official, who spoke on condition of anonymity because the issue is politically sensitive. “There may be conflicting information, but you don’t make the world safer by protecting people from ambiguity,” the official said.

As for keeping track of planes, there is agreement it needs to be done better, but no certainty on how to do that.

The U.N. agency and the International Air Transport Association, the world’s leading airline trade group, want long-haul flights over ocean to report their whereabouts every 15 minutes. If a plane deviates from its route or if there is some irregularity, the plane automatically would report its position every minute. That way an impact site should be within about 6 nautical miles of the last reported position.

Some airlines are balking at the potential cost. There also is disagreement over whether specific technology solutions should be required or whether airlines should be allowed to choose their own, so long as a plane can meet the reporting standard.

Malaysia Airlines 370 vanished en route from Kuala Lumpur to Beijing with 239 people aboard. The Boeing 777 was capable of reporting continuous location information by satellite, but the system was not in use. The plane is believed to have crashed in the Indian Ocean. More than 25,000 square miles of ocean have been searched, but nothing has been found.

Current global aviation standards require that airliners flying long distances over water report their position about every 45 minutes, but satellite services can provide more precise information. Customers of Spidertracks, a New Zealand company that provides satellite-based tracking mostly to charter operators flying to remote or dangerous parts of the world, can monitor the movements of planes in near real time on their smartphones or laptops and exchange two-way text messages with the aircraft.

Part of the need to find lost planes is for the recovery of flight data and cockpit voice recorders, also known as “black boxes,” to learn what happened.

European regulators and aircraft maker Airbus want planes equipped with black boxes that automatically eject and float to the surface in the event of a water crash. The boxes would have emergency locator transmitters, but there are doubts about their effectiveness.

Boeing officials, who oppose the idea, have told aviation forums that the company is unaware of a single instance in which one of its airliners has been found as the result of an emergency locator transmitter. The company wants the flexibility to decide which technologies work best.

One way to get around the need for floating black boxes would be for airliners to stream much of the data via satellite to ground stations or cloud data storage sites. But cost is a major factor, and there are concerns about privacy and security.

The National Transportation Safety Board has recommended that black boxes and flight tracking methods also be made tamper resistant. MH370’s transponder and other equipment that might have been used to track the plane shut down during the flight. Global aviation officials suspect they were deliberately turned off, but without the plane or its black boxes there is no way to know for certain.