Drones threatening commercial a/c?

[El Grifo]

Originally Posted by Mark in CA

Here's a report of a drone thought to have been deliberately flown close (within 80 feet) to a commercial aircraft on approach at London Southend Airport. This event follows an American report of a drone nearly colliding with a passenger plane near Tallahassee's airport in March of this year; that near-collision happened at an altitude of over 2,000 feet.

Report: Drone nearly collided with British passenger plane on purpose

Do drones of this size present much of a danger to these aircraft? Would they be roughly equivalent to a bird strike? Could colliding with one bring a plane down?

Apparently the UK's BALPA will have a representative speak before the House of Lords this week about their concerns, so it sounds serious.

How the heck can a delivery drone always remain in sight of the pilot unless the pilot follows it to its destination ???