Haas Team Principal Guenther Steiner has explained their bizarre technique to get their drivers to pit after an IT issue wiped out team communications.

Both Cars #8 and #20 were black flagged just inside the 20-minute mark of Practice 1 at the Monaco Grand Prix.

It was soon revealed that Haas had lost radio communications and telemetry for both Romain Grosjean and Kevin Magnussen, leading the team to revert to pit boards.

However, the drivers failed to see the old-fashioned equipment along the main straight, prompting Haas to think outside the box and asked stewards to display their two drivers a black flag.

“We had an issue with the IT equipment,” said Steiner.

“We had no data any more, nothing, no radio, we couldn’t contact them and we couldn’t see what the car was doing. They needed to come in quick.

“We put the pit board out, but they didn’t see it, so we came up with the idea to ask race control to give them the black flag so they’ll come in.

“That’s what we did. Everybody got a little too much excited about it.

A black flag requires the stated driver to return to the pit lane immediately, disqualifying them from the session. However, both Grosjean and Magnussen were excused and returned to the track late into the Thursday morning session.

“We were a little bit creative there,” Steiner added.

“(We) asked for some help to get them focused to come in.

“They got in, and then we fixed the problem and we got out the last 20 minutes.

“They should look at the pit board as well. I think they will now in future; if for more than five laps you don’t hear anything on the radio in Monte Carlo, something must be wrong!”

Magnussen ended Practice 2, the faster of the two sessions, in seventh while Grosjean was 11th in that afternoon session.

Practice 3 commences after the traditional Friday break on Saturday at 2000 AEST.