From another lawyer site.
Looks like you need to carry the I485 Receipt also, eventhough you travel using H1/L1.
Q. Can I travel after I file the AOS?
Yes. There are two ways to travel. You can apply to BCIS for Advance Parole or you can travel with a valid H-1B or L-1 visa as long as you have certain documents upon your return to the U.S.
a) Advance Parole. To obtain Advance Parole, you must file Form I-131 Application for Advance Parole with BCIS at the same time or after filing your AOS (BCIS Form I-485) application. This travel document must be issued prior to your departure from the U.S. and it must be presented at the port of entry along with your passport.
b) H-1B or L-1 Nonimmigrant Visa. You may also travel pursuant to your H-1B or L-1 status if you have the following upon entry to the U.S.: (1) a valid H-1B or L-1 visa stamp in your passport (unless Canadian and visa exempt) (2) an original H-1B or L-1 approval notice (unless you applied for admission on the basis of a blanket L-1 and have not since filed an extension) and (3) an original AOS receipt notice. In addition, you must also intend to continue to work for the same H or L employer upon your entry to the U.S. If your dependents are traveling, please note that in addition to the three items, they must also have a copy of your H or L visa petition approval notice as well as any BCIS H-4 or L-2 approval notices they received. Furthermore, if they plan to use the H-4/L-2 classifications, you must remain on H-1B/L-1 classification. If you use an advance parole, they cannot use the derivative nonimmigrant visa classifications and must use advance paroles.
It is important to note that it is currently taking BCIS several weeks to issue I-485 receipts. We understand that in light of the receipt processing time, it may be difficult to wait for the receipt notice before traveling. Please note, however, that the immigration regulations are very clear that if you enter the U.S. on an H or L visa without the AOS receipt, BCIS may deem your AOS application abandoned. This may require re-filing of your AOS application. Therefore, in light of the serious consequences, we recommend that you wait for the receipt before traveling.
