THE Singapore Flyer started turning again at about 11pm on Tuesday night after the observation wheel grounded to a halt because of a technical fault.

Some 173 people were stuck in the capsules of the Singapore Flyer for hours. The wheel stopped spinning at about 4.50pm and rescue operations continued on through the night.

Passengers were rappelled down from the capsules, starting from the cabin which was closest to the ground.

Ambulances and Singapore Civil Defence Force crews were also on hand, but there were no reports of any injuries or medical emergencies.

Even before rescue efforts were in full swing, requests started to come down from the passengers via the intercom for food and also pails so that they could relieve themsleves.

As the drama continued overhead, relatives and friends of the passgeners gathered below, including a couple who were about to exchange their wedding vows in one of the capsules.

It is unclear at this time what caused the problem, but The Straits Times understands that there is a backup generator in case of a power disruption.

And even if that fails, similar observation wheels are designed such that it would not take more than a few people to manually spin it.

There have been at least two other earlier reported incidents when passengers were stuck midair after the $240 million Singapore Flyer stopped spinning.

The first incident in July lasted 30 minutes and more recent on Dec 4, it took five hours for operatons to resume.

A ride on the 165m-tall wheel - about 42 storeys high - typically takes half an hour, and each of the 28 capsules can take up to 28 people.

Every capsule is equipped with the system, which is linked to the control room, allowing passengers and the control room personnel to communicate.

There are also surveillance cameras installed in every capsule.

The Singapore Flyer which started operations in February this year was expected to draw some 2.5 million people in its first year.