|Position||Search and rescue helicopter|
|Arrived on Sodor||Unknown|
Harold is the search and rescue helicopter who helps anyone in distress during an emergency. His home base is at an airfield in Dryaw.
Harold helped out getting two injured workmen to hospital after Oliver brought Clarabel to the top station on Thomas' Branch Line during the eighth Season 1 episode, Little Western. This was Harold's first appearance in the entire series.
In Search Engines, Harold said to Diesel that he did a good job in finding a woman who went missing for a few days. He picked her up from the bottom of the viaduct and was taken to hospital for her injured arm when she slipped and fell off a cliff she tried to climb back up to get to her car. It was Diesel's guard who called for Harold at the nearest signal box with permission from the signalman.
In Medivac, Harold had to abandon his flying skills outside the main line because of bad weather and had to take an injured fisherman to Knapford hospital. Donald and Douglas, the Scottish twins got his attention and took the patient along with his doctor, Harry Sullivan on their brake van all the way to Knapford station where the ambulance is waiting for the patient to be picked up from platform two. The Fat Controller was impressed by the twins' efforts and re-opened the Kirk Ronan Branch Line as his major prize.
In the feature-length special Winds of Change, Harold flew over the site of Gordon's accident with a stalled lorry just outside East Knapford station. Emily Helen Hatt came with the emergency team on Bear as Henry took the re-railed coaches back to the station and acting controller Norman Spencer who was at the scene spoke to the woman about what happened and had agreed to do a media report for tonight as said by the woman.
In Aftermath, Harold was told to airlift the victims of a car crash to the hospital that was nearest to one of the towns. The helicopter flew off after being given permission to airlift them by an ambulance officer while the investigation continues with Percy taking Thomas back to Tidmouth following the crash at the level crossing with the cause unlikely to conclude.
Harold is based on a Sikorsky H-19 Chickasaw (commercial designation S-55) with added floats.
- Season 1 - Little Western
- Season 2 - Old Tricks
- Season 3 - Search Engines and Christmas Delivery (stock footage, cameo)
- Season 4 - Medivac and Decisions (stock footage, does not speak)
- Season 1 STMY - Aftermath
- Winds of Change (does not speak)