Emirates and Turkish Airways say they have been exempted from a US ban on laptops in airline cabins, joining Etihad in satisfying American security concerns that had cut into the long-haul carriers' business.
It remains unclear how the airlines addressed fears that Islamic State or other groups might smuggle explosives on board in electronic devices, but in Turkey, authorities now use CT scanners to take cross-section images of passengers' electronics just before they board planes heading to the US.
Both airlines alerted the Department of Homeland Security, which oversees plane safety in the US, that "they are ready to comply with the enhanced security measures", said David Lapan, a Homeland Security spokesman in Washington.
"Protecting the American people and raising the global baseline on aviation security remains the top priority," Mr Lapan said.
"We will continue to closely observe operations in these airports to ensure these enhanced measures are implemented effectively and to the required levels."
Emirates' hub at Dubai International Airport has grown into the world's busiest for international traffic, in large part thanks to Emirates' expansion.
On Wednesday, the airline said it had worked to "implement heightened security measures and protocols" to satisfy American requirements. It did not elaborate, following a similar precedent set by Abu Dhabi-based Etihad, which US officials cleared on Sunday.
"We would like to express our gratitude to the US and local authorities for their support and thank our customers for their understanding and patience during the last few months when the ban was in place," Emirates said.
In Istanbul, Turkish Airlines tweeted that passengers aboard its US-bound flights should "fasten your seatbelts and enjoy your own electronic devices".
A statement from the airline said it had taken more than 81,000 electronic devices away from passengers to store them in specially protected baggage during the 102 days the ban was in place.
The US laptop ban, announced in March, now applies to non-stop US-bound flights from seven international airports in Amman, Jordan; Kuwait City; Cairo, Egypt; Jeddah and Riyadh, Saudi Arabia; Casablanca, Morocco; and Doha, Qatar.