Travel journalist Simon Calder is at Gatwick this morning and has been speaking to BBC Breakfast.

He says he has spoken to passengers affected by the disruption.

Among those he spoke to was a woman trying to get to Morocco.

Mr Calder said: "It's her third day of waiting, just trying to get home to her family."

Asked why the drone had not been shot down, as some people had suggested, Mr Grayling said "we can't just fire weapons haphazardly in what is a built-up area around the airport".

Instead, he said, authorities had to "take steps that are do-able and safe".

Mr Grayling told Today that patrols are taking place around other airports to watch out for any other possible drone incidents.

He also said talks would be held with airports around the UK as soon as possible, regarding what had happened at Gatwick.

He said it could be the work of a group or an individual, yet to be identified.

"I don't want to speculate on that, we genuinely don't know who it is," he said when asked if a foreign state was responsible, though he added he thought that was "unlikely".

Image source, Getty Images

Transport Secretary Chris Grayling tells BBC Radio 4's Today programme the situation was one in which "there aren't simple solutions".

Asked why it had taken so long for the situation to be controlled, he said "this is an entirely new kind of threat".

"This is a new kind of attack we have to make sure we're prepared for," he added, saying police were following a number of leads.

Tom Pugh
BBC South East Digital Reporter

Image source, Tom Pugh

At Gatwick Airport’s South Terminal this morning, passengers waited anxiously for news on whether their flights would depart.

It appears to be much quieter here today, compared to the chaotic scenes which we reported yesterday.

As the West Sussex airport announced the reopening of its runway on Friday, some travellers were hopeful of getting airborne.

But others expressed concern that the operators of the drone had not yet been apprehended - and could go on to cause more havoc.

All weary travellers could do was monitor the arrival and departure boards which were showing many cancellations and delays to flights - and hope their Christmas getaways would not be ruined.

The airport says that "passengers must expect delays and cancellations again today."

Below is their latest statement in full.

Bazookas, nets and trained eagles are all used to tackle rogue drones around the world.

What is the risk posed to aircraft by drones and what should airports do to mitigate the threat?

Gatwick's runway has reopened after drones caused the airport to shut down for more than a day, and the airport appears to be a lot quieter this morning than it was yesterday.

Benoit Guilbaud was understandably bemused to find his boarding pass for a flight from Gatwick today featured an advert for drones.

This is what he tweeted last night:

Image source, Twitter/@BenGuildbaud

Image source, Twitter/@BenGuilbaud

Easyjet replied to the tweet, saying: "The advert was placed before the issues at Gatwick and has now been removed. We are sorry for any offence."

Asst Ch Con Steve Barry from Sussex Police said: "The last drone activity was seen at 22:00 last night."

He said no-one had been arrested, but police were following "several lines of inquiry".

"There are a range of options, some very sophisticated and others less sophisticated."

"We did have a pre-planned response. We have had previous minor incursions over the airport, but this has been unprecedented."

He said it was a possibility the recent events were an environmental protest.

At this stage we are not saying this is terrorism related."

Mr Grayling reassured passengers they were safe to fly, saying "a lot of detailed work has been done" and that the airport would not have taken the decision to reopen "if they were not confident".

Mr Grayling said he would be convening meetings with other UK airports in the near future.

He said the situation was "unprecedented, anywhere in the world".

Every possible measure will be put in place to make sure this can't happen again, the transport secretary added.

He said it was a criminal offence and that those responsible would face "several years in prison".

Transport Secretary Chris Grayling said there was no evidence the drone disruption was terror-related but clearly a type of disruption "we've not seen before."

He said that "lessons need to be learned."

He said the government has "put in place a mix of measures to give confidence that planes can be safe and give passengers confidence it is safe to fly."

Transport Secretary Chris Grayling tells BBC Breakfast: "There were more than 40 sightings over the period the airport was closed."

He added: "We're going to have to learn very quickly from what's happened."

Assistant Chief Constable Steve Barry tells BBC Breakfast: "This scenario we have been dealing with is unprecedented."

He added: "Some of the stories I read on social media last night were heartbreaking."

But he added that "safety has to come first."

"At this stage we're not saying that it's terror-related."

Gatwick's chief operating officer Chris Woodroofe has been speaking to Radio 4's Today programme.

He said there were just under 700 planned departures today, a reduction of more than 100 flights which have already been cancelled.

He said passengers should check with airlines before travelling to the airport.

Mr Woodroofe said 120,000 passengers due to arrive or fly have not travelled since Wednesday night.

No-one has been found responsible at this stage by police, he said.

"We have been working overnight with the police, government agencies and military to put in place additional mitigating measures," he said.

However Mr Woodroofe said he could not talk about operations in detail.

"Additional mitigating measures provided by government agencies and military have given me the confidence to reopen the airport," he said.

"My intention is to get those passengers to their destinations so that they can enjoy their Christmas."

He apologised to those affected over the past 36 hours.

When asked why has it taken so long to reopen the airport, Mr Woodroofe said "this incident has demonstrated that there needs to be an awful lot more done to prevent this risk of drones."