MPH: Mark Hughes on...

It was the first time we'd ever seen a Formula 1 car slalom flat-out through a slow-moving traffic jam. And it was terrifying. We are talking a speed differential of well over 100mph, many, many times greater than that which killed Gilles Villeneuve in 1982, an accident that was all about one driver cruising, another on a flat-out qualifying lap.

The regulations as currently configured are tailor-made to create exactly that situation. All it would have taken for an aircraft-style crash at Sepang on Saturday would have been one of the five drivers on their in-laps to have wandered a few feet off line, unaware even there was a car approaching them at racing speeds.

Heikki Kovalainen, Lewis Hamilton, Felipe Massa, Robert Kubica and Kimi Raikkonen were not expecting another car still on its qualifying lap. In their minds the session was over. So as Massa was acknowledging the crowd for a pole position he hadn't actually secured yet, he will doubtless have been surprised as the flat-chat Nick Heidfeld blasted past him, just as had the McLaren drivers a few seconds earlier when they'd baulked his approach to turn four.

Nick got through the traffic physically unscathed, the only damage being to his lap time, dropping him from a likely third fastest to seventh. Just behind him, Fernando Alonso was even more badly blocked. It was an incident that could so easily have ended in the medical centre rather than the stewards room.

Kovalainen and Hamilton were duly penalised five grid places, but that wasn't really a satisfactory resolution. It didn't give Heidfeld back the time he would have set had he not been baulked. His seventh fastest time became fifth on the grid - but unfettered he'd have been higher than that. Alonso made less of a fuss, reasoning that even without his delay he wouldn't have been any better than ninth fastest. That's just the way the time gaps fell. But the sporting inequities were dwarfed by the safety concerns.

The problem was triggered by the expectation of rain, and the frontrunners making their final qualifying runs early. But its roots are in the revised top-10 run-off format for this year. Eliminating the fuel credit laps and reducing the session from 15 minutes to 10 has had a profound effect on how teams run the session.

For one, with the elimination of the fuel burn there are no longer any inconsequential laps. Every lap is either a flying qualifier or an in- or out-lap. There's time for two flyers. Which, with the in- and out-laps, means six laps for each car, 10 cars = 60 laps in 10 minutes. It's always going to be very crowded. For another, because you no longer get fuel refill credits for the laps you complete, the fuel saved on in-laps is proportionately a much bigger part of the total - and therefore much more important.

So the teams have devised extreme fuel maps that cut cylinders alternately - just as McLaren innovated last year in order to be able to sit at the end of the pitlane for minutes on end without overheating. With the cylinder cut-outs and using just a whiff of throttle, the cars are crawling around painfully slowly on those in-laps, way slower than before. The situation is made potentially even more dangerous by these extreme fuel maps. It means the engines will have no grunt should a driver need to accelerate suddenly out of the way.

On Saturday, with rain expected at any moment, McLaren and Ferrari got their guys out as early as possible. Normally they'd wait, time their final runs just as the session's closing seconds were counting down in order to get the full benefit of the track rubbering in. So as the drivers finish their laps, the session is at an end. That's the habit the Ferrari and McLaren drivers have got into over the past year; if they're finished, the session's finished. That's how it usually goes. It's clear that on Saturday as they finished they'd plain forgotten that the session was still live. Heidfeld's and Alonso's crews had gambled that the rain was not going to fall and had timed their runs to be out there at the end, with the track at its grippiest. Hence the few scary seconds of conflict.

When the run-off session was introduced in 2006, there was initially a requirement in the regulations that all laps, including in- and out-laps, had to be within 110 per cent of the driver's best. Any laps falling outside of that target were not given a fuel credit. It was dropped quite early following a session that took place in variable weather conditions, making the comparisons meaningless.

There is still a rule in place that requires cars being driven to the grid to complete their laps within a set target time. This legislates against wildly differing speeds from those cars that have qualified in the top 10 and are therefore needing every bit of their fuel and those outside the top 10 who have been free to fuel up to whatever level is needed.

No one is really at fault here. The regulations have ended up where they are for the best of reasons. Saturday at Sepang simply highlighted an inadvertent and potentially lethal side effect. It's good that the problem was made vivid without anyone getting hurt, but it would be wrong now to ignore what happened. It is time for a required percentage time to be reintroduced for qualifying in-laps, probably with a lap time penalty for any offenders.