From the UK - British Airways fly from London Gatwick and Virgin Atlantic fly from London Heathrow.
From Europe - Condor fly from Frankfurt direct to Tobago, KLM fly from Amsterdam to Piarco International (POS).
From North America - WestJet fly from Toronto Canada. american Airlines fly from Washington, NYC and Miami. Caribbean Airlines fly from Toronto, NYC, Fort Lauderdale and Miami. United Airlines fly from Newark and Houston. Some of the above flights arrive at Piarco Trinidad so the inter island airbridge flight would be needed to get to Tobago.
From the Caribbean - Caribbean Airlines fly from Grenada, Barbados and Trinidad. LIAT and Caribbean Star fly from Barbados via Grenada and the late afternoon flights are timed for connections from the northern islands (St.Thomas, Tortola, St.Maarten, St.Kitts, Anguilla, Antigua & Barbuda, Dominica, Guadeloupe, Martinique and St.Lucia).
Trinidad and Tobago airbridge - flights start from Trinidad at 5.45AM and continue throughout the day until 12.55AM, the last flight arriving in Tobago at 1.20AM. The flight takes around 20 minutes, make sure to leave around 3 hours in between landing and departure when you arrive at POS, due to customs and border control.