Excellent article by Flying Mag:
“Do you ever look to the skies and wonder what airplanes are flying above you? If you have an iPhone 4S, you can simply ask Siri – the service that not only answers your questions, but actually talks back too. But apparently it’s important to use proper language when you talk to Siri, just like when you communicate with air traffic controllers.
Asking: “What flights are overhead?” will get the response “Sorry I can’t help you with flights.” But if you ask instead, “Ask Wolfram what flights are overhead,” you’ll get a list of overflying flights near your position. The data includes the registration number for general aviation flights or name of the operator and the flight number for commercial flights. There is also location data for each airplane such as, altitude, slant distance, cardinal or intercardinal direction and the angle above the horizon.
The information is also displayed graphically on a “sky map” – a circular display that covers a 360-degree viewing area, from horizon to horizon, and includes the location of the sun during the day and the moon and star constellations at night for reference.
If you’re wondering who Wolfram is, it is referring to WolframAlpha, one of several companies that power Siri’s intelligence. WolframAlpha is not a search engine but rather “an engine for computing answers and getting knowledge” according to the company’s website. You can access the same information regarding flights overhead on www.wolframalpha.com by typing “flights overhead,” and access even more information for each flight, such as destination and very detailed flight data at different times during the flight.”