The clouds at the top of the Empire State Building came close to ruining the famous couple's engagement
Credit: Dimitrios Kambouris/WireImage

As if proposing isn’t already nerve-wracking enough!

Peter Facinelli told PEOPLE on Tuesday about how his proposal last month to Thor actress Jaimie Alexander came scarily close to being ruined.

The Twilight star had arranged for a plane to fly by the top of the Empire State Building with a banner at 4 p.m.

“At 3:55 she was like, ‘I’m cold, I’m going to go inside,’ ” Facinelli, 41, says. “And then all of a sudden I look up when she went in and the plane was there!”

After bringing Alexander, 31, back out, he lost the plane in the clouds and figured it had passed.

“I had binoculars and I looked up and I saw a helicopter, and I looked and couldn’t find [the plane] because I was nervous that it had left,” Facinelli continues, “and then I gave the binoculars to her and she goes, ‘Yeah, it’s right there,’ and then she read the banner, so it worked out.”

Whew! And after the plane was finally spotted, did Facinelli finish up with a traditional proposal?

“I had just bought these new jeans and they were a little tight,” he says, “so I said, ‘My jeans are tight but I’ll try to get down on one knee.’ ”

The couple began dating in late 2012, and both are starring in upcoming NBC shows: Facinelli in American Odyssey and Alexander in Blindspot.