There are some subjects which laser/aviation safety experts agree pose no real hazard. These include passenger exposure to laser light, pilot distraction during cruising or other non-critical phases of flight, and laser damage to the aircraft.
The main concerns of safety experts are almost exclusively focused on laser and bright light effects on pilots, especially when they are in a critical phase of flight: takeoff, approach, landing, and emergency maneuvers.
There are four primary areas of concern. The first three are "visual effects" that temporarily distract or block pilots' vision. These effects are only of concern when the laser emits visible light.
Distraction and startle. An unexpected laser or bright light could distract the pilot during a nighttime landing or takeoff. A pilot might not know what was happening at first. They may be worried that a brighter light or other threat would be coming. It is important that pilots be trained to understand the relatively minor impact of laser flashes caused by laser pointers and not to over react.
Glare and disruption. As the light brightness increases, it starts to interfere with vision. Veiling glare would make it difficult to see out the windscreen. Night vision starts to deteriorate. Laser light is highly directional so that pilots may act to exclude the source from their direct field of vision if properly trained. Pointer lasers have an illuminance of about 1 lumen/m2 whereas during the day the pilots have to deal with sunlight which is one hundred thousand times stronger.
Temporary flash blindness. This works exactly like a bright camera flash: there is no injury, but night vision is temporarily knocked out. There may be afterimages—again, exactly like a bright camera flash leaving temporary spots.
The three visual effects above are the primary concern for aviation experts. This is because they could happen with lower-powered lasers that are commonly available. The fourth concern, eye damage, is much less likely. It would take specialized equipment not readily available to the general public.
Eye damage. Though it is unlikely, high power visible or invisible (infrared, ultraviolet) laser light could cause permanent eye injury. The injury could be relatively minor, such as spots only detectable by medical exam or on the periphery of vision. At higher power levels, the spots may be in the central vision, in the same area where the original light was viewed. Most unlikely of all is injury causing a complete and permanent loss of vision. To do this requires very specialized equipment and a desire to deliberately target aircraft.
It is extremely unlikely that any of the four elements above would cause loss of the aircraft, especially if the pilots react properly and work as a team.