Can helicopters safely fly when it is raining?

Question

A November 2018 story that has been recently resurrected in the media was about Donald Trump claiming that he didn't make a visit to the Aisne-Marne American Cemetery near Paris by helicopter because the weather was inappropriate for travel

• Metro UK, 4 September, 2020

Donald Trump has claimed it was too rainy for his presidential helicopter to fly him to a cemetery filled with US World War One soldiers. The president hit back at reports he’d canceled the 2018 trip after branding the Great War dead ‘losers’ and feared for his hairstyle, saying: ‘I went to Paris, I was all set to go.

‘They had a rainstorm the likes of which you’ve rarely seen. The fog was so great, it was as dense as I’ve ever seen and i almost knew that you couldn’t use the helicopter…the helicopter would have been very quick, but the helicopter could never fly in that weather.’

• New York Magazine, September 2020:

Bolton says the visit was canceled because the rain complicated helicopter travel, and the drive would have taken too long.

Would it have been risky/dangerous (at the level of care appropriate for a President) for that type of helicopter to have flown over that distance and terrain on that day?

Answer 1

On the one hand, I accept that Hollywood exaggerates ...

Funerals and somber events almost inevitably are portrayed as happening during slightly inclement weather in Hollywood movies. An umbrella is essential garb in a Hollywood depiction of a funeral or some other somber event.

This would have been a perfect photo op. The weather in Paris on 10 November 2018 ranged from no rain to drizzle to light rain, from partially sunny to mostly cloudy to cloudy to foggy, and from a light to gentle breeze. This would not have been an impediment to a well-equipped Sikorsky Sea King or Black Hawk, the two types of helicopters used as Marine-1.

Many other heads of state, including Angela Merkel, managed to find their way to the 100th anniversary of Armistice Day in spite of that slightly inclement weather. From The Guardian,

Under grey clouds and persistent drizzle, France’s president, Emmanuel Macron, and Germany’s chancellor, Angela Merkel, clasped hands at a solemn ceremony at Compiègne as they marked the centenary of the armistice signing.
On Saturday, as the French and German national anthems were played, the sun briefly broke through and the chancellor rested her head on the president’s. The two leaders laid a wreath and unveiled a plaque celebrating their reconciliation.

We do know that Marine-1 has flown at night. For example, President Trump returned from his June 20, 2020 rally in Tulsa, Oklahoma via Marine-1, at 1:00 AM local time on June 21. This means that at least that version of Marine-1 was not restricted by visual flight rules. While the exact equipment the Marine-1 helicopters (there are nine of them) are highly classified, it's hard to imagine that all of the nine helicopters are not similarly equipped.

It's also hard to imagine a more perfect photo op for such a somber event. That the weather was very slightly inclement made this a perfectly somber photo op. Hollywood is right: The weather is not supposed to be perfect for somber occasions such as this. And in this case, the weather cooperated with Hollywood.

Answer 2

Yes, they can fly in rain with no trouble at all and there is plenty of evidence to back this up. Of course in situations like this safety concerns are different because it would be the president of the united states on the helicopter but that doesn't change the fact that it is safe to fly in the rain.

https://www.theatlantic.com/ideas/archive/2018/11/can-trumps-helicopter-marine-one-fly-rain/575695/

There is nothing special about the rain-worthiness of the helicopter any president normally uses. In principle, any helicopter can fly in clouds or rain.

Of course, safety considerations are different when a president is traveling. The pilots and maintenance practices of Marine One are presumably the best that can be found, but the play-it-safe factor when carrying a president has to be larger than for other missions. So who knows whether some aviation official really said: Sorry, this is no-go.

https://www.avioninsurance.com/weather-affect-helicopter-flight-safety/

Rain, snow, sleet, and fog may not affect helicopter performance, but they generally obstruct visibility. These conditions may make take-off and landing more difficult and affect a pilot’s ability to see obstacles that are encountered during flight. Rain, snow, and sleet may also make conditions on the tarmac or landing pad slippery, which can be problematic.

https://www.aircraftcompare.com/blog/can-helicopters-fly-in-bad-weather/#:~:text=Helicopters%20generally%20have%20no%20issues%20flying%20in%20rain.&text=However%2C%20rain%20can%20impact%20the,it%20is%20safe%20to%20fly.

Helicopters generally have no issues flying in rain. Rain does not affect the thrust created by the blades needed for takeoff. However, rain can impact the visibility for the pilot substantially. It is up to the pilot to determine whether or not it is safe to fly.