Krishnan,
Please check the following web page for "visa on arrival" info.
http://www.germany.info/Vertretung/usa/en/04__Legal/02__Directory__Services/01__Visa/__Transit__Country__List__Visa.html
Exemption 4 to the list above
Travellers who do not intend to leave the transit lounge at a German airport and who do not have
a)a residence title of a member state of the European Union or a member state of the European Economic Area (EEA, i.e. Iceland, Liechtenstein and Norway) or
b)a permanent residence permit of Andorra, Japn, Canada, Monaco, San Marino, Switzerland or the USA (only green cards with 10 years`validity or unlimited validity will qualify)
require a transit visa.
Until further notice a Visa on arrival will be issued for them by the competent authorities at the respective German airport.
If you are still in doubt whether you need an airport transit visa, do not hesitate to call the German mission which serves your place of residence in the US.
Although this information has been prepared with utmost care, the we can not accept any responsibility for inaccuracies contained herein.
Although this information has been prepared with utmost care, the we can not accept any responsibility for inaccuracies contained herein.